diff --git a/Tests/LibWeb/Text/data/blank.html b/Tests/LibWeb/Text/data/blank.html
index e69de29bb2d..0e76edd65b7 100644
--- a/Tests/LibWeb/Text/data/blank.html
+++ b/Tests/LibWeb/Text/data/blank.html
@@ -0,0 +1 @@
+<!DOCTYPE html>
diff --git a/Tests/LibWeb/Text/data/history-pushstate-iframe.html b/Tests/LibWeb/Text/data/history-pushstate-iframe.html
index 1f227bb5238..1c989f0d835 100644
--- a/Tests/LibWeb/Text/data/history-pushstate-iframe.html
+++ b/Tests/LibWeb/Text/data/history-pushstate-iframe.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script>
     try {
         const initialHistoryLength = window.history.length;
diff --git a/Tests/LibWeb/Text/data/iframe-popstate-event.html b/Tests/LibWeb/Text/data/iframe-popstate-event.html
index 24ea968ac29..73557335c01 100644
--- a/Tests/LibWeb/Text/data/iframe-popstate-event.html
+++ b/Tests/LibWeb/Text/data/iframe-popstate-event.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script>
     window.history.pushState({}, '', window.location.href + '#test');
 
diff --git a/Tests/LibWeb/Text/data/iframe-reload.html b/Tests/LibWeb/Text/data/iframe-reload.html
index d7194d2ae62..726780453f4 100644
--- a/Tests/LibWeb/Text/data/iframe-reload.html
+++ b/Tests/LibWeb/Text/data/iframe-reload.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script>
     window.addEventListener('message', event => {
         if (event.data && event.data.action === 'reload') {
diff --git a/Tests/LibWeb/Text/data/iframe-test-content-1.html b/Tests/LibWeb/Text/data/iframe-test-content-1.html
index 77d9d100753..38324387a30 100644
--- a/Tests/LibWeb/Text/data/iframe-test-content-1.html
+++ b/Tests/LibWeb/Text/data/iframe-test-content-1.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script>
     parent.postMessage("message from test iframe (1)", "*");
 </script>
diff --git a/Tests/LibWeb/Text/data/iframe-test-content-2.html b/Tests/LibWeb/Text/data/iframe-test-content-2.html
index d651bcbb303..18617ae0ee3 100644
--- a/Tests/LibWeb/Text/data/iframe-test-content-2.html
+++ b/Tests/LibWeb/Text/data/iframe-test-content-2.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script>
     parent.postMessage("message from test iframe (2)", "*");
 </script>
diff --git a/Tests/LibWeb/Text/data/iframe-with-border-radius-svg.html b/Tests/LibWeb/Text/data/iframe-with-border-radius-svg.html
index 62434fc1be0..c5f4c5863a8 100644
--- a/Tests/LibWeb/Text/data/iframe-with-border-radius-svg.html
+++ b/Tests/LibWeb/Text/data/iframe-with-border-radius-svg.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <style>
     div {
         background-image: url('data:image/svg+xml;utf8,<svg version="1.1" xmlns="http://www.w3.org/2000/svg"></svg>');
diff --git a/Tests/LibWeb/Text/data/local-storage-iframe.html b/Tests/LibWeb/Text/data/local-storage-iframe.html
index f87199395fe..8f5b218e7a9 100644
--- a/Tests/LibWeb/Text/data/local-storage-iframe.html
+++ b/Tests/LibWeb/Text/data/local-storage-iframe.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script>
     localStorage.setItem("foo", "barbaz");
     parent.postMessage("local storage set", "*");
diff --git a/Tests/LibWeb/Text/data/navigation-navigate-iframe.html b/Tests/LibWeb/Text/data/navigation-navigate-iframe.html
index 6bfcc111085..4433c7d621c 100644
--- a/Tests/LibWeb/Text/data/navigation-navigate-iframe.html
+++ b/Tests/LibWeb/Text/data/navigation-navigate-iframe.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script>
     function filename(path) {
         url = new URL(path)
diff --git a/Tests/LibWeb/Text/data/test-iframe-content.html b/Tests/LibWeb/Text/data/test-iframe-content.html
index cdd289246e1..c0c7bd6aac8 100644
--- a/Tests/LibWeb/Text/data/test-iframe-content.html
+++ b/Tests/LibWeb/Text/data/test-iframe-content.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <body>
     hello!
 </body>
diff --git a/Tests/LibWeb/Text/data/video-gc-frame.html b/Tests/LibWeb/Text/data/video-gc-frame.html
index 61f90724110..b6105c6f761 100644
--- a/Tests/LibWeb/Text/data/video-gc-frame.html
+++ b/Tests/LibWeb/Text/data/video-gc-frame.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <video id="video" autoplay src="../../Assets/test-webm.webm"></video>
 <script type="text/javascript">
     video.addEventListener("loadedmetadata", () => {
diff --git a/Tests/LibWeb/Text/input/Attr-cloneNode.html b/Tests/LibWeb/Text/input/Attr-cloneNode.html
index b66935671b9..bc130b5fb87 100644
--- a/Tests/LibWeb/Text/input/Attr-cloneNode.html
+++ b/Tests/LibWeb/Text/input/Attr-cloneNode.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <script>
   test(() => {
diff --git a/Tests/LibWeb/Text/input/CSSOMView/getClientRects-in-detached-document.html b/Tests/LibWeb/Text/input/CSSOMView/getClientRects-in-detached-document.html
index 6c139aa0751..47f73866775 100644
--- a/Tests/LibWeb/Text/input/CSSOMView/getClientRects-in-detached-document.html
+++ b/Tests/LibWeb/Text/input/CSSOMView/getClientRects-in-detached-document.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/Clipboard/clipboarditem.html b/Tests/LibWeb/Text/input/Clipboard/clipboarditem.html
index d4da5a61eab..4b440e0a01d 100644
--- a/Tests/LibWeb/Text/input/Clipboard/clipboarditem.html
+++ b/Tests/LibWeb/Text/input/Clipboard/clipboarditem.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script type="text/javascript">
     asyncTest(async (done) => {
diff --git a/Tests/LibWeb/Text/input/Compression/DecompressionStream.html b/Tests/LibWeb/Text/input/Compression/DecompressionStream.html
index 116682e7d14..a71ec3c13d1 100644
--- a/Tests/LibWeb/Text/input/Compression/DecompressionStream.html
+++ b/Tests/LibWeb/Text/input/Compression/DecompressionStream.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest(async done => {
diff --git a/Tests/LibWeb/Text/input/Compression/round-trip.html b/Tests/LibWeb/Text/input/Compression/round-trip.html
index 2a34bd82ef8..31be2cd770b 100644
--- a/Tests/LibWeb/Text/input/Compression/round-trip.html
+++ b/Tests/LibWeb/Text/input/Compression/round-trip.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     function readStream(reader) {
diff --git a/Tests/LibWeb/Text/input/Crypto/SubtleCrypto-deriveBits.html b/Tests/LibWeb/Text/input/Crypto/SubtleCrypto-deriveBits.html
index 91e6ae7157a..8f9a1caba9f 100644
--- a/Tests/LibWeb/Text/input/Crypto/SubtleCrypto-deriveBits.html
+++ b/Tests/LibWeb/Text/input/Crypto/SubtleCrypto-deriveBits.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest(async done => {
diff --git a/Tests/LibWeb/Text/input/Crypto/SubtleCrypto-digest.html b/Tests/LibWeb/Text/input/Crypto/SubtleCrypto-digest.html
index d468efb762a..640de6fe941 100644
--- a/Tests/LibWeb/Text/input/Crypto/SubtleCrypto-digest.html
+++ b/Tests/LibWeb/Text/input/Crypto/SubtleCrypto-digest.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     function bufferToHex(buffer) {
diff --git a/Tests/LibWeb/Text/input/Crypto/SubtleCrypto-encrypt.html b/Tests/LibWeb/Text/input/Crypto/SubtleCrypto-encrypt.html
index 94f3b10ad86..9c1550a908d 100644
--- a/Tests/LibWeb/Text/input/Crypto/SubtleCrypto-encrypt.html
+++ b/Tests/LibWeb/Text/input/Crypto/SubtleCrypto-encrypt.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest(async done => {
diff --git a/Tests/LibWeb/Text/input/Crypto/SubtleCrypto-exportKey.html b/Tests/LibWeb/Text/input/Crypto/SubtleCrypto-exportKey.html
index d84ef85089c..051ff91fa99 100644
--- a/Tests/LibWeb/Text/input/Crypto/SubtleCrypto-exportKey.html
+++ b/Tests/LibWeb/Text/input/Crypto/SubtleCrypto-exportKey.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     function bufferToHex(buffer) {
diff --git a/Tests/LibWeb/Text/input/Crypto/SubtleCrypto-generateKey.html b/Tests/LibWeb/Text/input/Crypto/SubtleCrypto-generateKey.html
index 1701b8a78f1..bfd3cbebbeb 100644
--- a/Tests/LibWeb/Text/input/Crypto/SubtleCrypto-generateKey.html
+++ b/Tests/LibWeb/Text/input/Crypto/SubtleCrypto-generateKey.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     function bufferToHex(buffer) {
diff --git a/Tests/LibWeb/Text/input/Crypto/SubtleCrypto-hmac.html b/Tests/LibWeb/Text/input/Crypto/SubtleCrypto-hmac.html
index 9934bd0f062..f2e247e16ac 100644
--- a/Tests/LibWeb/Text/input/Crypto/SubtleCrypto-hmac.html
+++ b/Tests/LibWeb/Text/input/Crypto/SubtleCrypto-hmac.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest(async done => {
diff --git a/Tests/LibWeb/Text/input/Crypto/SubtleCrypto-import-PBKDF2.html b/Tests/LibWeb/Text/input/Crypto/SubtleCrypto-import-PBKDF2.html
index acafb6576b6..e38cc9f78df 100644
--- a/Tests/LibWeb/Text/input/Crypto/SubtleCrypto-import-PBKDF2.html
+++ b/Tests/LibWeb/Text/input/Crypto/SubtleCrypto-import-PBKDF2.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     function bufferToHex(buffer) {
diff --git a/Tests/LibWeb/Text/input/Crypto/SubtleCrypto-import-export-roundtrip.html b/Tests/LibWeb/Text/input/Crypto/SubtleCrypto-import-export-roundtrip.html
index 8607b09038d..cd9621e90af 100644
--- a/Tests/LibWeb/Text/input/Crypto/SubtleCrypto-import-export-roundtrip.html
+++ b/Tests/LibWeb/Text/input/Crypto/SubtleCrypto-import-export-roundtrip.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest(async (done) => {
diff --git a/Tests/LibWeb/Text/input/Crypto/SubtleCrypto-sign.html b/Tests/LibWeb/Text/input/Crypto/SubtleCrypto-sign.html
index 83442d84a0e..374349ee423 100644
--- a/Tests/LibWeb/Text/input/Crypto/SubtleCrypto-sign.html
+++ b/Tests/LibWeb/Text/input/Crypto/SubtleCrypto-sign.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest(async done => {
diff --git a/Tests/LibWeb/Text/input/Crypto/SubtleCrypto-verify.html b/Tests/LibWeb/Text/input/Crypto/SubtleCrypto-verify.html
index a1bf43ebd83..64dffa33514 100644
--- a/Tests/LibWeb/Text/input/Crypto/SubtleCrypto-verify.html
+++ b/Tests/LibWeb/Text/input/Crypto/SubtleCrypto-verify.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest(async done => {
diff --git a/Tests/LibWeb/Text/input/DOM/CDATASection-assignedSlot.html b/Tests/LibWeb/Text/input/DOM/CDATASection-assignedSlot.html
index 5f9924de3c9..aebcf6ca251 100644
--- a/Tests/LibWeb/Text/input/DOM/CDATASection-assignedSlot.html
+++ b/Tests/LibWeb/Text/input/DOM/CDATASection-assignedSlot.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/DOM/CDATASection-cloneNode.html b/Tests/LibWeb/Text/input/DOM/CDATASection-cloneNode.html
index 942d366860c..f4a5b62a569 100644
--- a/Tests/LibWeb/Text/input/DOM/CDATASection-cloneNode.html
+++ b/Tests/LibWeb/Text/input/DOM/CDATASection-cloneNode.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/DOM/CharacterData-replaceData-break-surrogate-pair.html b/Tests/LibWeb/Text/input/DOM/CharacterData-replaceData-break-surrogate-pair.html
index be07b2b5753..f3af0e9f92a 100644
--- a/Tests/LibWeb/Text/input/DOM/CharacterData-replaceData-break-surrogate-pair.html
+++ b/Tests/LibWeb/Text/input/DOM/CharacterData-replaceData-break-surrogate-pair.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/DOM/CharacterData-substringData-break-surrogate-pair.html b/Tests/LibWeb/Text/input/DOM/CharacterData-substringData-break-surrogate-pair.html
index fb8328b1e85..e4a287caef8 100644
--- a/Tests/LibWeb/Text/input/DOM/CharacterData-substringData-break-surrogate-pair.html
+++ b/Tests/LibWeb/Text/input/DOM/CharacterData-substringData-break-surrogate-pair.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/DOM/ChildNode-after-next-sibling.html b/Tests/LibWeb/Text/input/DOM/ChildNode-after-next-sibling.html
index 10b63d5a508..0419033d072 100644
--- a/Tests/LibWeb/Text/input/DOM/ChildNode-after-next-sibling.html
+++ b/Tests/LibWeb/Text/input/DOM/ChildNode-after-next-sibling.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div id="one"></div><div id="two"></div><script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/DOM/ChildNode-before-previous-sibling.html b/Tests/LibWeb/Text/input/DOM/ChildNode-before-previous-sibling.html
index ca9e02ed24f..e1b2cd43c0c 100644
--- a/Tests/LibWeb/Text/input/DOM/ChildNode-before-previous-sibling.html
+++ b/Tests/LibWeb/Text/input/DOM/ChildNode-before-previous-sibling.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div id="one"></div><div id="two"></div><script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/DOM/DOMImplementation-create-xml-document.html b/Tests/LibWeb/Text/input/DOM/DOMImplementation-create-xml-document.html
index db1bbf52cd6..b448fbe80ce 100644
--- a/Tests/LibWeb/Text/input/DOM/DOMImplementation-create-xml-document.html
+++ b/Tests/LibWeb/Text/input/DOM/DOMImplementation-create-xml-document.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/DOM/DOMImplementation-createHTMLDocument.html b/Tests/LibWeb/Text/input/DOM/DOMImplementation-createHTMLDocument.html
index b5b70000e9a..05ee7657af3 100644
--- a/Tests/LibWeb/Text/input/DOM/DOMImplementation-createHTMLDocument.html
+++ b/Tests/LibWeb/Text/input/DOM/DOMImplementation-createHTMLDocument.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <body>
 <script src="../include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/DOM/DOMParser-xml-document.html b/Tests/LibWeb/Text/input/DOM/DOMParser-xml-document.html
index 699feb9a5c8..89711e2ff36 100644
--- a/Tests/LibWeb/Text/input/DOM/DOMParser-xml-document.html
+++ b/Tests/LibWeb/Text/input/DOM/DOMParser-xml-document.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/DOM/DOMStringMap-setter-with-invalid-name.html b/Tests/LibWeb/Text/input/DOM/DOMStringMap-setter-with-invalid-name.html
index f5bd116db20..56150a9f5b9 100644
--- a/Tests/LibWeb/Text/input/DOM/DOMStringMap-setter-with-invalid-name.html
+++ b/Tests/LibWeb/Text/input/DOM/DOMStringMap-setter-with-invalid-name.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/DOM/Delete-from-text-node-with-associated-range.html b/Tests/LibWeb/Text/input/DOM/Delete-from-text-node-with-associated-range.html
index 1d24e7fe049..cac2f3eb407 100644
--- a/Tests/LibWeb/Text/input/DOM/Delete-from-text-node-with-associated-range.html
+++ b/Tests/LibWeb/Text/input/DOM/Delete-from-text-node-with-associated-range.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/DOM/Document-createCDATASection.html b/Tests/LibWeb/Text/input/DOM/Document-createCDATASection.html
index befeacf070c..c8433596d8d 100644
--- a/Tests/LibWeb/Text/input/DOM/Document-createCDATASection.html
+++ b/Tests/LibWeb/Text/input/DOM/Document-createCDATASection.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/DOM/Document-dir.html b/Tests/LibWeb/Text/input/DOM/Document-dir.html
index 7aec4c5f4cc..ff9ececfa2e 100644
--- a/Tests/LibWeb/Text/input/DOM/Document-dir.html
+++ b/Tests/LibWeb/Text/input/DOM/Document-dir.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/DOM/Document-named-properties.html b/Tests/LibWeb/Text/input/DOM/Document-named-properties.html
index 08c8997bf3e..7c83a6b76f6 100644
--- a/Tests/LibWeb/Text/input/DOM/Document-named-properties.html
+++ b/Tests/LibWeb/Text/input/DOM/Document-named-properties.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <form name="bob">
     <button type="submit" id="fred" name="george" value="submit">Submit</button>
 </form>
diff --git a/Tests/LibWeb/Text/input/DOM/Document-set-designMode.html b/Tests/LibWeb/Text/input/DOM/Document-set-designMode.html
index df7cb3335e0..4d522977b3f 100644
--- a/Tests/LibWeb/Text/input/DOM/Document-set-designMode.html
+++ b/Tests/LibWeb/Text/input/DOM/Document-set-designMode.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>    
     function setDesignMode(value) {
diff --git a/Tests/LibWeb/Text/input/DOM/Element-getAttributeNS.html b/Tests/LibWeb/Text/input/DOM/Element-getAttributeNS.html
index b2c5d3652b8..71e87b1e0d7 100644
--- a/Tests/LibWeb/Text/input/DOM/Element-getAttributeNS.html
+++ b/Tests/LibWeb/Text/input/DOM/Element-getAttributeNS.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <svg xmlns="http://www.w3.org/2000/svg">
     <script id="with-xlink-href" xlink:href="test"></script>
diff --git a/Tests/LibWeb/Text/input/DOM/Element-getAttributeNodeNS.html b/Tests/LibWeb/Text/input/DOM/Element-getAttributeNodeNS.html
index 5cb4f15d9f0..c4f6f8f61b9 100644
--- a/Tests/LibWeb/Text/input/DOM/Element-getAttributeNodeNS.html
+++ b/Tests/LibWeb/Text/input/DOM/Element-getAttributeNodeNS.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <svg xmlns="http://www.w3.org/2000/svg">
     <script id="with-xlink-href" xlink:href="test"></script>
diff --git a/Tests/LibWeb/Text/input/DOM/Element-removeAttributeNS.html b/Tests/LibWeb/Text/input/DOM/Element-removeAttributeNS.html
index 2a15b57fbc2..9c28cd9ef06 100644
--- a/Tests/LibWeb/Text/input/DOM/Element-removeAttributeNS.html
+++ b/Tests/LibWeb/Text/input/DOM/Element-removeAttributeNS.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <svg xmlns="http://www.w3.org/2000/svg">
     <script id="with-xlink-href" xlink:href="test"></script>
diff --git a/Tests/LibWeb/Text/input/DOM/Element-removeAttributeNode.html b/Tests/LibWeb/Text/input/DOM/Element-removeAttributeNode.html
index 56a2904f21b..b449c9594a6 100644
--- a/Tests/LibWeb/Text/input/DOM/Element-removeAttributeNode.html
+++ b/Tests/LibWeb/Text/input/DOM/Element-removeAttributeNode.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/DOM/Element-set-scroll-left.html b/Tests/LibWeb/Text/input/DOM/Element-set-scroll-left.html
index 68d1f7da17f..9bbb24cfe3b 100644
--- a/Tests/LibWeb/Text/input/DOM/Element-set-scroll-left.html
+++ b/Tests/LibWeb/Text/input/DOM/Element-set-scroll-left.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <style>
     .scrollable-div {
         width: 100%;
diff --git a/Tests/LibWeb/Text/input/DOM/Element-setAttribute-capitalization.html b/Tests/LibWeb/Text/input/DOM/Element-setAttribute-capitalization.html
index e4cd2208725..381afaebc11 100644
--- a/Tests/LibWeb/Text/input/DOM/Element-setAttribute-capitalization.html
+++ b/Tests/LibWeb/Text/input/DOM/Element-setAttribute-capitalization.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
   test(() => {
diff --git a/Tests/LibWeb/Text/input/DOM/Element-setAttribute-name-validation.html b/Tests/LibWeb/Text/input/DOM/Element-setAttribute-name-validation.html
index eb40a48cdd9..b3b47d089db 100644
--- a/Tests/LibWeb/Text/input/DOM/Element-setAttribute-name-validation.html
+++ b/Tests/LibWeb/Text/input/DOM/Element-setAttribute-name-validation.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/DOM/Element-toggleAttribute-xml-doc-html-ns.html b/Tests/LibWeb/Text/input/DOM/Element-toggleAttribute-xml-doc-html-ns.html
index 6f5980bf8dc..7a3bc8a5f86 100644
--- a/Tests/LibWeb/Text/input/DOM/Element-toggleAttribute-xml-doc-html-ns.html
+++ b/Tests/LibWeb/Text/input/DOM/Element-toggleAttribute-xml-doc-html-ns.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/DOM/Elements-from-point-3.html b/Tests/LibWeb/Text/input/DOM/Elements-from-point-3.html
index bd304b5dbbd..55006e61d21 100644
--- a/Tests/LibWeb/Text/input/DOM/Elements-from-point-3.html
+++ b/Tests/LibWeb/Text/input/DOM/Elements-from-point-3.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <div>
     <p>Some text</p>
 </div>
diff --git a/Tests/LibWeb/Text/input/DOM/FormAssociatedElement-selection-type-change.html b/Tests/LibWeb/Text/input/DOM/FormAssociatedElement-selection-type-change.html
index 73a1d8cb31c..dcd97cf47f5 100644
--- a/Tests/LibWeb/Text/input/DOM/FormAssociatedElement-selection-type-change.html
+++ b/Tests/LibWeb/Text/input/DOM/FormAssociatedElement-selection-type-change.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <input type="text" id="input" value="12389" />
 <script src="../include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/DOM/FormAssociatedElement-selection.html b/Tests/LibWeb/Text/input/DOM/FormAssociatedElement-selection.html
index 33a70c7135b..4c00529d24f 100644
--- a/Tests/LibWeb/Text/input/DOM/FormAssociatedElement-selection.html
+++ b/Tests/LibWeb/Text/input/DOM/FormAssociatedElement-selection.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <input type="text" id="text-input">
 <input type="date" id="date-input">
 <textarea id="textarea">some
diff --git a/Tests/LibWeb/Text/input/DOM/HTMLCollection-empty-string-as-property-name.html b/Tests/LibWeb/Text/input/DOM/HTMLCollection-empty-string-as-property-name.html
index 259d4d49dd6..7a0d1a5052b 100644
--- a/Tests/LibWeb/Text/input/DOM/HTMLCollection-empty-string-as-property-name.html
+++ b/Tests/LibWeb/Text/input/DOM/HTMLCollection-empty-string-as-property-name.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div id></div>
 <div id=haxx></div>
diff --git a/Tests/LibWeb/Text/input/DOM/HTMLCollection-order.html b/Tests/LibWeb/Text/input/DOM/HTMLCollection-order.html
index 915d0de48a9..395e98b4df9 100644
--- a/Tests/LibWeb/Text/input/DOM/HTMLCollection-order.html
+++ b/Tests/LibWeb/Text/input/DOM/HTMLCollection-order.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <a name="anchor1" id="foo"></a>
 <a name="anchor2" id="baz"></a>
 <a name="anchor3" id="anchor1"></a>
diff --git a/Tests/LibWeb/Text/input/DOM/HTMLCollection-property-names-iteration-order.html b/Tests/LibWeb/Text/input/DOM/HTMLCollection-property-names-iteration-order.html
index 7d9205c3b94..44ce7c13bf1 100644
--- a/Tests/LibWeb/Text/input/DOM/HTMLCollection-property-names-iteration-order.html
+++ b/Tests/LibWeb/Text/input/DOM/HTMLCollection-property-names-iteration-order.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <a name="foo"></a>
 <a name="bar"></a>
 <a name="baz"></a>
diff --git a/Tests/LibWeb/Text/input/DOM/HTMLSelectElement-length.html b/Tests/LibWeb/Text/input/DOM/HTMLSelectElement-length.html
index 78eb617820e..0f4fbdd272c 100644
--- a/Tests/LibWeb/Text/input/DOM/HTMLSelectElement-length.html
+++ b/Tests/LibWeb/Text/input/DOM/HTMLSelectElement-length.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/DOM/Range-containing-CDATASection.html b/Tests/LibWeb/Text/input/DOM/Range-containing-CDATASection.html
index 1502ae9101f..5d84b6aebc0 100644
--- a/Tests/LibWeb/Text/input/DOM/Range-containing-CDATASection.html
+++ b/Tests/LibWeb/Text/input/DOM/Range-containing-CDATASection.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/DOM/Range-to-string.html b/Tests/LibWeb/Text/input/DOM/Range-to-string.html
index b75757ab3ca..70fa143ff10 100644
--- a/Tests/LibWeb/Text/input/DOM/Range-to-string.html
+++ b/Tests/LibWeb/Text/input/DOM/Range-to-string.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <body><p id="p1"><b>Hello💨</b>😮 World</p>
 <script src="../include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/DOM/Text-methods.html b/Tests/LibWeb/Text/input/DOM/Text-methods.html
index 2fb149be2b9..63fdb5f91ed 100644
--- a/Tests/LibWeb/Text/input/DOM/Text-methods.html
+++ b/Tests/LibWeb/Text/input/DOM/Text-methods.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/DOM/Text-set-get-data.html b/Tests/LibWeb/Text/input/DOM/Text-set-get-data.html
index 1e42507eaaa..485ec62e950 100644
--- a/Tests/LibWeb/Text/input/DOM/Text-set-get-data.html
+++ b/Tests/LibWeb/Text/input/DOM/Text-set-get-data.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/DOM/TreeWalker-nextNode-with-detached-currentNode.html b/Tests/LibWeb/Text/input/DOM/TreeWalker-nextNode-with-detached-currentNode.html
index 4fcc83a8447..563a70729d4 100644
--- a/Tests/LibWeb/Text/input/DOM/TreeWalker-nextNode-with-detached-currentNode.html
+++ b/Tests/LibWeb/Text/input/DOM/TreeWalker-nextNode-with-detached-currentNode.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/DOM/cloneNode-with-goofy-attribute.html b/Tests/LibWeb/Text/input/DOM/cloneNode-with-goofy-attribute.html
index d15be31cd87..f746f5d3f48 100644
--- a/Tests/LibWeb/Text/input/DOM/cloneNode-with-goofy-attribute.html
+++ b/Tests/LibWeb/Text/input/DOM/cloneNode-with-goofy-attribute.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <svg><circle id=c a(></svg>
 <script>
diff --git a/Tests/LibWeb/Text/input/DOM/createElement-with-emoji-in-tag-name.html b/Tests/LibWeb/Text/input/DOM/createElement-with-emoji-in-tag-name.html
index edac3a49ee8..863c1ede33d 100644
--- a/Tests/LibWeb/Text/input/DOM/createElement-with-emoji-in-tag-name.html
+++ b/Tests/LibWeb/Text/input/DOM/createElement-with-emoji-in-tag-name.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/DOM/createEvent-hashchangeevent.html b/Tests/LibWeb/Text/input/DOM/createEvent-hashchangeevent.html
index 43c851a4a2d..40be424aa31 100644
--- a/Tests/LibWeb/Text/input/DOM/createEvent-hashchangeevent.html
+++ b/Tests/LibWeb/Text/input/DOM/createEvent-hashchangeevent.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/DOM/derived-interface-prototype.html b/Tests/LibWeb/Text/input/DOM/derived-interface-prototype.html
index e366f62b0da..af2c9697183 100644
--- a/Tests/LibWeb/Text/input/DOM/derived-interface-prototype.html
+++ b/Tests/LibWeb/Text/input/DOM/derived-interface-prototype.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/DOM/domparser-parsefromstring-xml-empty-pubid.html b/Tests/LibWeb/Text/input/DOM/domparser-parsefromstring-xml-empty-pubid.html
index 97d6fe0863a..60b6b730f12 100644
--- a/Tests/LibWeb/Text/input/DOM/domparser-parsefromstring-xml-empty-pubid.html
+++ b/Tests/LibWeb/Text/input/DOM/domparser-parsefromstring-xml-empty-pubid.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/DOM/domparser-parsefromstring-xml-empty-systemid.html b/Tests/LibWeb/Text/input/DOM/domparser-parsefromstring-xml-empty-systemid.html
index 84aa9544d03..ad81de0019f 100644
--- a/Tests/LibWeb/Text/input/DOM/domparser-parsefromstring-xml-empty-systemid.html
+++ b/Tests/LibWeb/Text/input/DOM/domparser-parsefromstring-xml-empty-systemid.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/DOM/getElementById-multiple.html b/Tests/LibWeb/Text/input/DOM/getElementById-multiple.html
index adcc0b3b9ec..57b47505583 100644
--- a/Tests/LibWeb/Text/input/DOM/getElementById-multiple.html
+++ b/Tests/LibWeb/Text/input/DOM/getElementById-multiple.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <div id="foo" n="1"></div><div id="foo" n="2"></div>
 <script src="../include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/DOM/range-bounding-client-rect-with-nested-text.html b/Tests/LibWeb/Text/input/DOM/range-bounding-client-rect-with-nested-text.html
index ec3cae1eb88..4e9b4e9915d 100644
--- a/Tests/LibWeb/Text/input/DOM/range-bounding-client-rect-with-nested-text.html
+++ b/Tests/LibWeb/Text/input/DOM/range-bounding-client-rect-with-nested-text.html
@@ -1,5 +1,5 @@
-<!--refer to https://wpt.live/css/cssom-view/range-bounding-client-rect-with-nested-text.html -->
 <!DOCTYPE html>
+<!--refer to https://wpt.live/css/cssom-view/range-bounding-client-rect-with-nested-text.html -->
 <meta charset="utf-8">
 <title>All the rectangles for the text nodes must included in getClientRects</title>
 <script src="../include.js"></script>
diff --git a/Tests/LibWeb/Text/input/DOM/range-get-client-rects.html b/Tests/LibWeb/Text/input/DOM/range-get-client-rects.html
index dcfd402af0b..ed687b12965 100644
--- a/Tests/LibWeb/Text/input/DOM/range-get-client-rects.html
+++ b/Tests/LibWeb/Text/input/DOM/range-get-client-rects.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <!--refer to https://wpt.live/css/cssom-view/DOMRectList.html -->
 <body>
 <div id="x">x</div>
diff --git a/Tests/LibWeb/Text/input/DOM/setAttribute-with-emoji-in-attribute-name.html b/Tests/LibWeb/Text/input/DOM/setAttribute-with-emoji-in-attribute-name.html
index f9b39779417..126b4121550 100644
--- a/Tests/LibWeb/Text/input/DOM/setAttribute-with-emoji-in-attribute-name.html
+++ b/Tests/LibWeb/Text/input/DOM/setAttribute-with-emoji-in-attribute-name.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/DOM/update-live-ranges-on-node-insertion.html b/Tests/LibWeb/Text/input/DOM/update-live-ranges-on-node-insertion.html
index 8153a93e2e9..ea50ec96c6a 100644
--- a/Tests/LibWeb/Text/input/DOM/update-live-ranges-on-node-insertion.html
+++ b/Tests/LibWeb/Text/input/DOM/update-live-ranges-on-node-insertion.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/Editing/beforeinput-event.html b/Tests/LibWeb/Text/input/Editing/beforeinput-event.html
index 56dfa6ac185..afe130ae761 100644
--- a/Tests/LibWeb/Text/input/Editing/beforeinput-event.html
+++ b/Tests/LibWeb/Text/input/Editing/beforeinput-event.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <style>
     #input {
diff --git a/Tests/LibWeb/Text/input/Editing/execCommand-backColor.html b/Tests/LibWeb/Text/input/Editing/execCommand-backColor.html
index d485ec35c9d..4e11b3430f1 100644
--- a/Tests/LibWeb/Text/input/Editing/execCommand-backColor.html
+++ b/Tests/LibWeb/Text/input/Editing/execCommand-backColor.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div contenteditable="true">foobar</div>
 <script>
diff --git a/Tests/LibWeb/Text/input/Editing/execCommand-bold.html b/Tests/LibWeb/Text/input/Editing/execCommand-bold.html
index 89ebd8a89b4..87b4bf1f3d1 100644
--- a/Tests/LibWeb/Text/input/Editing/execCommand-bold.html
+++ b/Tests/LibWeb/Text/input/Editing/execCommand-bold.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div contenteditable="true">foobar</div>
 <script>
diff --git a/Tests/LibWeb/Text/input/Editing/execCommand-createLink.html b/Tests/LibWeb/Text/input/Editing/execCommand-createLink.html
index 3c24db1f5a5..4bfc01fa7cc 100644
--- a/Tests/LibWeb/Text/input/Editing/execCommand-createLink.html
+++ b/Tests/LibWeb/Text/input/Editing/execCommand-createLink.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div contenteditable="true" id="d1">foobar</div>
 <div contenteditable="true" id="d2"><a href="https://ladybird.dev">ladybird</a></div>
diff --git a/Tests/LibWeb/Text/input/Editing/execCommand-delete.html b/Tests/LibWeb/Text/input/Editing/execCommand-delete.html
index bb26a787099..91f22511c88 100644
--- a/Tests/LibWeb/Text/input/Editing/execCommand-delete.html
+++ b/Tests/LibWeb/Text/input/Editing/execCommand-delete.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div contenteditable="true">foobar</div>
 <script>
diff --git a/Tests/LibWeb/Text/input/Editing/execCommand-fontName.html b/Tests/LibWeb/Text/input/Editing/execCommand-fontName.html
index 1ed21216331..a4ca40d729b 100644
--- a/Tests/LibWeb/Text/input/Editing/execCommand-fontName.html
+++ b/Tests/LibWeb/Text/input/Editing/execCommand-fontName.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div contenteditable="true">foobar</div>
 <script>
diff --git a/Tests/LibWeb/Text/input/Editing/execCommand-fontSize.html b/Tests/LibWeb/Text/input/Editing/execCommand-fontSize.html
index f8508dbf870..3762854c576 100644
--- a/Tests/LibWeb/Text/input/Editing/execCommand-fontSize.html
+++ b/Tests/LibWeb/Text/input/Editing/execCommand-fontSize.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div contenteditable="true">foobar</div>
 <script>
diff --git a/Tests/LibWeb/Text/input/Editing/execCommand-foreColor.html b/Tests/LibWeb/Text/input/Editing/execCommand-foreColor.html
index c1e534dae5e..8fe0f53df82 100644
--- a/Tests/LibWeb/Text/input/Editing/execCommand-foreColor.html
+++ b/Tests/LibWeb/Text/input/Editing/execCommand-foreColor.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div contenteditable="true">foobar</div>
 <script>
diff --git a/Tests/LibWeb/Text/input/Editing/execCommand-formatBlock.html b/Tests/LibWeb/Text/input/Editing/execCommand-formatBlock.html
index 022f48beff8..754e811030c 100644
--- a/Tests/LibWeb/Text/input/Editing/execCommand-formatBlock.html
+++ b/Tests/LibWeb/Text/input/Editing/execCommand-formatBlock.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div contenteditable="true">
     <div id="d1">foo<br>bar</div>
diff --git a/Tests/LibWeb/Text/input/Editing/execCommand-forwardDelete.html b/Tests/LibWeb/Text/input/Editing/execCommand-forwardDelete.html
index 039eaa2951d..0fecb6bfa5f 100644
--- a/Tests/LibWeb/Text/input/Editing/execCommand-forwardDelete.html
+++ b/Tests/LibWeb/Text/input/Editing/execCommand-forwardDelete.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div contenteditable="true">foobar</div>
 <script>
diff --git a/Tests/LibWeb/Text/input/Editing/execCommand-indent.html b/Tests/LibWeb/Text/input/Editing/execCommand-indent.html
index a1303f4dfa7..45595b75040 100644
--- a/Tests/LibWeb/Text/input/Editing/execCommand-indent.html
+++ b/Tests/LibWeb/Text/input/Editing/execCommand-indent.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div contenteditable="true">
     <span>foobar</span>
diff --git a/Tests/LibWeb/Text/input/Editing/execCommand-insertHTML.html b/Tests/LibWeb/Text/input/Editing/execCommand-insertHTML.html
index 1de609aa892..7bcc3c9587b 100644
--- a/Tests/LibWeb/Text/input/Editing/execCommand-insertHTML.html
+++ b/Tests/LibWeb/Text/input/Editing/execCommand-insertHTML.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div contenteditable="true">foobar</div>
 <script>
diff --git a/Tests/LibWeb/Text/input/Editing/execCommand-insertHorizontalRule.html b/Tests/LibWeb/Text/input/Editing/execCommand-insertHorizontalRule.html
index 6f1be5ffa7f..ab13c3cf645 100644
--- a/Tests/LibWeb/Text/input/Editing/execCommand-insertHorizontalRule.html
+++ b/Tests/LibWeb/Text/input/Editing/execCommand-insertHorizontalRule.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div contenteditable="true">foobar</div>
 <script>
diff --git a/Tests/LibWeb/Text/input/Editing/execCommand-insertImage.html b/Tests/LibWeb/Text/input/Editing/execCommand-insertImage.html
index 15e93b16873..7def66c08ea 100644
--- a/Tests/LibWeb/Text/input/Editing/execCommand-insertImage.html
+++ b/Tests/LibWeb/Text/input/Editing/execCommand-insertImage.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div contenteditable="true">foobar</div>
 <script>
diff --git a/Tests/LibWeb/Text/input/Editing/execCommand-insertLinebreak.html b/Tests/LibWeb/Text/input/Editing/execCommand-insertLinebreak.html
index 81bc658b50c..398f1abbee1 100644
--- a/Tests/LibWeb/Text/input/Editing/execCommand-insertLinebreak.html
+++ b/Tests/LibWeb/Text/input/Editing/execCommand-insertLinebreak.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div id="a" contenteditable>foobar</div>
 <div id="b" contenteditable><p style="white-space: pre">foobar</p></div>
diff --git a/Tests/LibWeb/Text/input/Editing/execCommand-insertOrderedList.html b/Tests/LibWeb/Text/input/Editing/execCommand-insertOrderedList.html
index 9a483ff82bf..343464aae0a 100644
--- a/Tests/LibWeb/Text/input/Editing/execCommand-insertOrderedList.html
+++ b/Tests/LibWeb/Text/input/Editing/execCommand-insertOrderedList.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div contenteditable="true" id="d1">foobar</div>
 <div contenteditable="true" id="d2"><ol><li>foobar</li></ol></div>
diff --git a/Tests/LibWeb/Text/input/Editing/execCommand-insertParagraph.html b/Tests/LibWeb/Text/input/Editing/execCommand-insertParagraph.html
index cf8a72d0ead..2c1d9ade6f1 100644
--- a/Tests/LibWeb/Text/input/Editing/execCommand-insertParagraph.html
+++ b/Tests/LibWeb/Text/input/Editing/execCommand-insertParagraph.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div contenteditable="true"><ul><li>foobar</li></ul></div>
 <script>
diff --git a/Tests/LibWeb/Text/input/Editing/execCommand-insertText.html b/Tests/LibWeb/Text/input/Editing/execCommand-insertText.html
index e5c1e0c7833..1b5051e4f0c 100644
--- a/Tests/LibWeb/Text/input/Editing/execCommand-insertText.html
+++ b/Tests/LibWeb/Text/input/Editing/execCommand-insertText.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div contenteditable="true">foobar</div>
 <script>
diff --git a/Tests/LibWeb/Text/input/Editing/execCommand-insertUnorderedList.html b/Tests/LibWeb/Text/input/Editing/execCommand-insertUnorderedList.html
index 7633668c97d..94aaec1f598 100644
--- a/Tests/LibWeb/Text/input/Editing/execCommand-insertUnorderedList.html
+++ b/Tests/LibWeb/Text/input/Editing/execCommand-insertUnorderedList.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div contenteditable="true" id="d1">foobar</div>
 <div contenteditable="true" id="d2"><ul><li>foobar</li></ul></div>
diff --git a/Tests/LibWeb/Text/input/Editing/execCommand-italic.html b/Tests/LibWeb/Text/input/Editing/execCommand-italic.html
index 45b21a97495..eb82fc08513 100644
--- a/Tests/LibWeb/Text/input/Editing/execCommand-italic.html
+++ b/Tests/LibWeb/Text/input/Editing/execCommand-italic.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div contenteditable="true">foobar</div>
 <script>
diff --git a/Tests/LibWeb/Text/input/Editing/execCommand-justifyCenter.html b/Tests/LibWeb/Text/input/Editing/execCommand-justifyCenter.html
index fd94a4357b8..42c1dd57f4f 100644
--- a/Tests/LibWeb/Text/input/Editing/execCommand-justifyCenter.html
+++ b/Tests/LibWeb/Text/input/Editing/execCommand-justifyCenter.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div contenteditable="true" id="d1">foobar</div>
 <div contenteditable="true" id="d2"><div style="text-align: right">foobar</div></div>
diff --git a/Tests/LibWeb/Text/input/Editing/execCommand-justifyFull.html b/Tests/LibWeb/Text/input/Editing/execCommand-justifyFull.html
index eb893d94671..62a035c22f8 100644
--- a/Tests/LibWeb/Text/input/Editing/execCommand-justifyFull.html
+++ b/Tests/LibWeb/Text/input/Editing/execCommand-justifyFull.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div contenteditable="true" id="d1">foobar</div>
 <div contenteditable="true" id="d2"><div style="text-align: right">foobar</div></div>
diff --git a/Tests/LibWeb/Text/input/Editing/execCommand-justifyLeft.html b/Tests/LibWeb/Text/input/Editing/execCommand-justifyLeft.html
index 92b9275d003..ccd17b1c2cc 100644
--- a/Tests/LibWeb/Text/input/Editing/execCommand-justifyLeft.html
+++ b/Tests/LibWeb/Text/input/Editing/execCommand-justifyLeft.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div contenteditable="true" id="d1">foobar</div>
 <div contenteditable="true" id="d2"><div style="text-align: right">foobar</div></div>
diff --git a/Tests/LibWeb/Text/input/Editing/execCommand-justifyRight.html b/Tests/LibWeb/Text/input/Editing/execCommand-justifyRight.html
index 06fd2535eb6..a8b00678226 100644
--- a/Tests/LibWeb/Text/input/Editing/execCommand-justifyRight.html
+++ b/Tests/LibWeb/Text/input/Editing/execCommand-justifyRight.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div contenteditable="true" id="d1">foobar</div>
 <div contenteditable="true" id="d2"><div style="text-align: left">foobar</div></div>
diff --git a/Tests/LibWeb/Text/input/Editing/execCommand-no-recursion.html b/Tests/LibWeb/Text/input/Editing/execCommand-no-recursion.html
index d3baa7c12cf..a3597aea954 100644
--- a/Tests/LibWeb/Text/input/Editing/execCommand-no-recursion.html
+++ b/Tests/LibWeb/Text/input/Editing/execCommand-no-recursion.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div contenteditable="true"></div>
 <script>
diff --git a/Tests/LibWeb/Text/input/Editing/execCommand-outdent.html b/Tests/LibWeb/Text/input/Editing/execCommand-outdent.html
index b169f34ce83..f7e11b491ea 100644
--- a/Tests/LibWeb/Text/input/Editing/execCommand-outdent.html
+++ b/Tests/LibWeb/Text/input/Editing/execCommand-outdent.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div contenteditable="true">
     <ul><li>foobar</li></ul>
diff --git a/Tests/LibWeb/Text/input/Editing/execCommand-removeFormat.html b/Tests/LibWeb/Text/input/Editing/execCommand-removeFormat.html
index efa4abdb49f..af34005e547 100644
--- a/Tests/LibWeb/Text/input/Editing/execCommand-removeFormat.html
+++ b/Tests/LibWeb/Text/input/Editing/execCommand-removeFormat.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div contenteditable="true">f<b>o</b>ob<i>a</i>r</div>
 <script>
diff --git a/Tests/LibWeb/Text/input/Editing/execCommand-selectAll.html b/Tests/LibWeb/Text/input/Editing/execCommand-selectAll.html
index f4744eb7e01..340a88a1bcd 100644
--- a/Tests/LibWeb/Text/input/Editing/execCommand-selectAll.html
+++ b/Tests/LibWeb/Text/input/Editing/execCommand-selectAll.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div contenteditable="true">
     <span>foobar</span>
diff --git a/Tests/LibWeb/Text/input/Editing/execCommand-strikethrough.html b/Tests/LibWeb/Text/input/Editing/execCommand-strikethrough.html
index 7c37150124a..b9925b66bbd 100644
--- a/Tests/LibWeb/Text/input/Editing/execCommand-strikethrough.html
+++ b/Tests/LibWeb/Text/input/Editing/execCommand-strikethrough.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div contenteditable="true">foobar</div>
 <script>
diff --git a/Tests/LibWeb/Text/input/Editing/execCommand-subscript.html b/Tests/LibWeb/Text/input/Editing/execCommand-subscript.html
index 7c829e079b9..951571cc011 100644
--- a/Tests/LibWeb/Text/input/Editing/execCommand-subscript.html
+++ b/Tests/LibWeb/Text/input/Editing/execCommand-subscript.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div contenteditable="true">foobar</div>
 <script>
diff --git a/Tests/LibWeb/Text/input/Editing/execCommand-superscript.html b/Tests/LibWeb/Text/input/Editing/execCommand-superscript.html
index 2dc419f85b8..ee62094ab2f 100644
--- a/Tests/LibWeb/Text/input/Editing/execCommand-superscript.html
+++ b/Tests/LibWeb/Text/input/Editing/execCommand-superscript.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div contenteditable="true">foobar</div>
 <script>
diff --git a/Tests/LibWeb/Text/input/Editing/execCommand-underline.html b/Tests/LibWeb/Text/input/Editing/execCommand-underline.html
index 5a1ef1aae51..7d661d9a189 100644
--- a/Tests/LibWeb/Text/input/Editing/execCommand-underline.html
+++ b/Tests/LibWeb/Text/input/Editing/execCommand-underline.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div contenteditable="true">foobar</div>
 <script>
diff --git a/Tests/LibWeb/Text/input/Editing/execCommand-unlink.html b/Tests/LibWeb/Text/input/Editing/execCommand-unlink.html
index 78058cf39b3..d4edae7d81d 100644
--- a/Tests/LibWeb/Text/input/Editing/execCommand-unlink.html
+++ b/Tests/LibWeb/Text/input/Editing/execCommand-unlink.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div contenteditable="true" id="d1"><a href="https://ladybird.dev">ladybird</a></div>
 <div contenteditable="true" id="d2">lady<a href="https://ladybird.dev">bird</a></div>
diff --git a/Tests/LibWeb/Text/input/Editing/input-event.html b/Tests/LibWeb/Text/input/Editing/input-event.html
index 864130debc0..019ad5ff6a7 100644
--- a/Tests/LibWeb/Text/input/Editing/input-event.html
+++ b/Tests/LibWeb/Text/input/Editing/input-event.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <style>
     #input {
diff --git a/Tests/LibWeb/Text/input/Editing/input-into-empty-contenteditable.html b/Tests/LibWeb/Text/input/Editing/input-into-empty-contenteditable.html
index d30213f7885..a64d1a8fc33 100644
--- a/Tests/LibWeb/Text/input/Editing/input-into-empty-contenteditable.html
+++ b/Tests/LibWeb/Text/input/Editing/input-into-empty-contenteditable.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <style>
     #input {
diff --git a/Tests/LibWeb/Text/input/Editing/move-cursor-using-selection-api.html b/Tests/LibWeb/Text/input/Editing/move-cursor-using-selection-api.html
index 5abfdc282c8..fa779e5572e 100644
--- a/Tests/LibWeb/Text/input/Editing/move-cursor-using-selection-api.html
+++ b/Tests/LibWeb/Text/input/Editing/move-cursor-using-selection-api.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div id="text" contenteditable="true">heo</div>
 <script>
diff --git a/Tests/LibWeb/Text/input/Editing/selection-in-contenteditable-crash-regression.html b/Tests/LibWeb/Text/input/Editing/selection-in-contenteditable-crash-regression.html
index fd4d25ad364..f2b43724341 100644
--- a/Tests/LibWeb/Text/input/Editing/selection-in-contenteditable-crash-regression.html
+++ b/Tests/LibWeb/Text/input/Editing/selection-in-contenteditable-crash-regression.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <style>
     div {
diff --git a/Tests/LibWeb/Text/input/Encoding/TextDecoder-decode.html b/Tests/LibWeb/Text/input/Encoding/TextDecoder-decode.html
index 4a2273770ce..f394c6ab3bf 100644
--- a/Tests/LibWeb/Text/input/Encoding/TextDecoder-decode.html
+++ b/Tests/LibWeb/Text/input/Encoding/TextDecoder-decode.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/Encoding/TextEncoder-encode.html b/Tests/LibWeb/Text/input/Encoding/TextEncoder-encode.html
index 3ac885502a5..5f9f0c9a2e0 100644
--- a/Tests/LibWeb/Text/input/Encoding/TextEncoder-encode.html
+++ b/Tests/LibWeb/Text/input/Encoding/TextEncoder-encode.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/Fetch/fetch-request-url-search-params.html b/Tests/LibWeb/Text/input/Fetch/fetch-request-url-search-params.html
index 0c6346dbd08..9b94d067b54 100644
--- a/Tests/LibWeb/Text/input/Fetch/fetch-request-url-search-params.html
+++ b/Tests/LibWeb/Text/input/Fetch/fetch-request-url-search-params.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script type="text/javascript">
     asyncTest(async done => {
diff --git a/Tests/LibWeb/Text/input/Fetch/fetch-response-content-type.html b/Tests/LibWeb/Text/input/Fetch/fetch-response-content-type.html
index 42f8720a360..06714643ce9 100644
--- a/Tests/LibWeb/Text/input/Fetch/fetch-response-content-type.html
+++ b/Tests/LibWeb/Text/input/Fetch/fetch-response-content-type.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/Fetch/fetch-response-url-encoded.html b/Tests/LibWeb/Text/input/Fetch/fetch-response-url-encoded.html
index fe9370fb7ce..4cfecbd6dc5 100644
--- a/Tests/LibWeb/Text/input/Fetch/fetch-response-url-encoded.html
+++ b/Tests/LibWeb/Text/input/Fetch/fetch-response-url-encoded.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest(done => {
diff --git a/Tests/LibWeb/Text/input/FileAPI/Blob-empty-constructor.html b/Tests/LibWeb/Text/input/FileAPI/Blob-empty-constructor.html
index 891d7b51bdb..cdd8c9d74a3 100644
--- a/Tests/LibWeb/Text/input/FileAPI/Blob-empty-constructor.html
+++ b/Tests/LibWeb/Text/input/FileAPI/Blob-empty-constructor.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/FileAPI/Blob-intialized-with-strings-read-from-arrayBuffer.html b/Tests/LibWeb/Text/input/FileAPI/Blob-intialized-with-strings-read-from-arrayBuffer.html
index 93078390194..fe4a1995c4d 100644
--- a/Tests/LibWeb/Text/input/FileAPI/Blob-intialized-with-strings-read-from-arrayBuffer.html
+++ b/Tests/LibWeb/Text/input/FileAPI/Blob-intialized-with-strings-read-from-arrayBuffer.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest(async (done) => {
diff --git a/Tests/LibWeb/Text/input/FileAPI/Blob-intialized-with-strings-read-from-bytes.html b/Tests/LibWeb/Text/input/FileAPI/Blob-intialized-with-strings-read-from-bytes.html
index 2a8a02a8de3..3d0cdb30fe6 100644
--- a/Tests/LibWeb/Text/input/FileAPI/Blob-intialized-with-strings-read-from-bytes.html
+++ b/Tests/LibWeb/Text/input/FileAPI/Blob-intialized-with-strings-read-from-bytes.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest(async (done) => {
diff --git a/Tests/LibWeb/Text/input/FileAPI/Blob-intialized-with-strings-read-from-text.html b/Tests/LibWeb/Text/input/FileAPI/Blob-intialized-with-strings-read-from-text.html
index 308f714b9d1..7c6ea6882eb 100644
--- a/Tests/LibWeb/Text/input/FileAPI/Blob-intialized-with-strings-read-from-text.html
+++ b/Tests/LibWeb/Text/input/FileAPI/Blob-intialized-with-strings-read-from-text.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest(async (done) => {
diff --git a/Tests/LibWeb/Text/input/FileAPI/Blob-partitioning.html b/Tests/LibWeb/Text/input/FileAPI/Blob-partitioning.html
index a00df69f46f..e9328c246cb 100644
--- a/Tests/LibWeb/Text/input/FileAPI/Blob-partitioning.html
+++ b/Tests/LibWeb/Text/input/FileAPI/Blob-partitioning.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest(async (done) => {
diff --git a/Tests/LibWeb/Text/input/FileAPI/filereader-basic.html b/Tests/LibWeb/Text/input/FileAPI/filereader-basic.html
index b354ef342e5..61cf004afa5 100644
--- a/Tests/LibWeb/Text/input/FileAPI/filereader-basic.html
+++ b/Tests/LibWeb/Text/input/FileAPI/filereader-basic.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest((done) => {
diff --git a/Tests/LibWeb/Text/input/HTML/CanvasRenderingContext2D-get-image-data-correctness.html b/Tests/LibWeb/Text/input/HTML/CanvasRenderingContext2D-get-image-data-correctness.html
index 485eab9c1de..ecffab58ba9 100644
--- a/Tests/LibWeb/Text/input/HTML/CanvasRenderingContext2D-get-image-data-correctness.html
+++ b/Tests/LibWeb/Text/input/HTML/CanvasRenderingContext2D-get-image-data-correctness.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/HTML/CloseWatcher-detached-iframe.html b/Tests/LibWeb/Text/input/HTML/CloseWatcher-detached-iframe.html
index f38db99981c..0311b02cbad 100644
--- a/Tests/LibWeb/Text/input/HTML/CloseWatcher-detached-iframe.html
+++ b/Tests/LibWeb/Text/input/HTML/CloseWatcher-detached-iframe.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     promiseTest(async () => {
diff --git a/Tests/LibWeb/Text/input/HTML/DOMParser-parseFromString-document-url.html b/Tests/LibWeb/Text/input/HTML/DOMParser-parseFromString-document-url.html
index f3cacc504a3..8b092bf6118 100644
--- a/Tests/LibWeb/Text/input/HTML/DOMParser-parseFromString-document-url.html
+++ b/Tests/LibWeb/Text/input/HTML/DOMParser-parseFromString-document-url.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/HTML/DedicatedWorkerGlobalScope-instanceof.html b/Tests/LibWeb/Text/input/HTML/DedicatedWorkerGlobalScope-instanceof.html
index 4636e216735..bf8e2d191a4 100644
--- a/Tests/LibWeb/Text/input/HTML/DedicatedWorkerGlobalScope-instanceof.html
+++ b/Tests/LibWeb/Text/input/HTML/DedicatedWorkerGlobalScope-instanceof.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest(done => {
diff --git a/Tests/LibWeb/Text/input/HTML/Element-insertAdjacentHTML-documentElement.html b/Tests/LibWeb/Text/input/HTML/Element-insertAdjacentHTML-documentElement.html
index 66de31038f9..79ef5b281ec 100644
--- a/Tests/LibWeb/Text/input/HTML/Element-insertAdjacentHTML-documentElement.html
+++ b/Tests/LibWeb/Text/input/HTML/Element-insertAdjacentHTML-documentElement.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/HTML/Form-indexed-property-access.html b/Tests/LibWeb/Text/input/HTML/Form-indexed-property-access.html
index e4795c9c6c7..1dfdaf916b4 100644
--- a/Tests/LibWeb/Text/input/HTML/Form-indexed-property-access.html
+++ b/Tests/LibWeb/Text/input/HTML/Form-indexed-property-access.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <form id="formy">
     <input type="text" name="foo">
     <button type="button" name="bar"></button>
diff --git a/Tests/LibWeb/Text/input/HTML/Form-named-property-access.html b/Tests/LibWeb/Text/input/HTML/Form-named-property-access.html
index 1f928a5ae06..e46ca0bf49e 100644
--- a/Tests/LibWeb/Text/input/HTML/Form-named-property-access.html
+++ b/Tests/LibWeb/Text/input/HTML/Form-named-property-access.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <form id="formy">
     <input type="text" name="foo">
     <button type="button" name="bar"></button>
diff --git a/Tests/LibWeb/Text/input/HTML/FormData-append-blob-with-type.html b/Tests/LibWeb/Text/input/HTML/FormData-append-blob-with-type.html
index bef15b20a1d..cfb731c93d7 100644
--- a/Tests/LibWeb/Text/input/HTML/FormData-append-blob-with-type.html
+++ b/Tests/LibWeb/Text/input/HTML/FormData-append-blob-with-type.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/HTML/FormData-append-with-emoji-in-name.html b/Tests/LibWeb/Text/input/HTML/FormData-append-with-emoji-in-name.html
index e0bfb210bce..e303869d5f5 100644
--- a/Tests/LibWeb/Text/input/HTML/FormData-append-with-emoji-in-name.html
+++ b/Tests/LibWeb/Text/input/HTML/FormData-append-with-emoji-in-name.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <div id=test></div>
 <script src="../include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/HTML/HTMLAllCollection-basic.html b/Tests/LibWeb/Text/input/HTML/HTMLAllCollection-basic.html
index bf1b7c77c0c..1a76aed77fb 100644
--- a/Tests/LibWeb/Text/input/HTML/HTMLAllCollection-basic.html
+++ b/Tests/LibWeb/Text/input/HTML/HTMLAllCollection-basic.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <form>
   <input name="one" id="formcontrol" type="button" />
   <input name="two" id="formcontrol" type="text" />
diff --git a/Tests/LibWeb/Text/input/HTML/HTMLElement-click.html b/Tests/LibWeb/Text/input/HTML/HTMLElement-click.html
index 1258c11d400..9e31c2cc056 100644
--- a/Tests/LibWeb/Text/input/HTML/HTMLElement-click.html
+++ b/Tests/LibWeb/Text/input/HTML/HTMLElement-click.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <button id="myButton"></button>
 <script>
diff --git a/Tests/LibWeb/Text/input/HTML/HTMLElement-isContentEditable.html b/Tests/LibWeb/Text/input/HTML/HTMLElement-isContentEditable.html
index fcac25e82f7..d64b6131ace 100644
--- a/Tests/LibWeb/Text/input/HTML/HTMLElement-isContentEditable.html
+++ b/Tests/LibWeb/Text/input/HTML/HTMLElement-isContentEditable.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div contenteditable="true" id="contenteditable"></div>
 <script>
diff --git a/Tests/LibWeb/Text/input/HTML/HTMLElement-offsetFoo-for-split-inline-element.html b/Tests/LibWeb/Text/input/HTML/HTMLElement-offsetFoo-for-split-inline-element.html
index 8612950e432..f3152fb4121 100644
--- a/Tests/LibWeb/Text/input/HTML/HTMLElement-offsetFoo-for-split-inline-element.html
+++ b/Tests/LibWeb/Text/input/HTML/HTMLElement-offsetFoo-for-split-inline-element.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <b>foo<div>bar</div>baz</b>
 <script src="../include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/HTML/HTMLElement-offsetFoo-in-table-cell.html b/Tests/LibWeb/Text/input/HTML/HTMLElement-offsetFoo-in-table-cell.html
index 415988ebb35..8cf5050335e 100644
--- a/Tests/LibWeb/Text/input/HTML/HTMLElement-offsetFoo-in-table-cell.html
+++ b/Tests/LibWeb/Text/input/HTML/HTMLElement-offsetFoo-in-table-cell.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <style>
 * {
     margin: 0;
diff --git a/Tests/LibWeb/Text/input/HTML/HTMLFrameElement-add-remove.html b/Tests/LibWeb/Text/input/HTML/HTMLFrameElement-add-remove.html
index 0abd829cec0..da3d3cf0ff0 100644
--- a/Tests/LibWeb/Text/input/HTML/HTMLFrameElement-add-remove.html
+++ b/Tests/LibWeb/Text/input/HTML/HTMLFrameElement-add-remove.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <head>
     <script src="../include.js"></script>
     <script>
diff --git a/Tests/LibWeb/Text/input/HTML/HTMLFrameElement-load.html b/Tests/LibWeb/Text/input/HTML/HTMLFrameElement-load.html
index 1384059978d..bfc3673130d 100644
--- a/Tests/LibWeb/Text/input/HTML/HTMLFrameElement-load.html
+++ b/Tests/LibWeb/Text/input/HTML/HTMLFrameElement-load.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <head>
     <script src="../include.js"></script>
     <script>
diff --git a/Tests/LibWeb/Text/input/HTML/HTMLInputElement-valueAsNumber.html b/Tests/LibWeb/Text/input/HTML/HTMLInputElement-valueAsNumber.html
index 9ffe7679b47..3e0e47ebd35 100644
--- a/Tests/LibWeb/Text/input/HTML/HTMLInputElement-valueAsNumber.html
+++ b/Tests/LibWeb/Text/input/HTML/HTMLInputElement-valueAsNumber.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <input id="input-element" value="100" style="display: none;" />
 <script src="../include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/HTML/HTMLLinkElement-blob-url.html b/Tests/LibWeb/Text/input/HTML/HTMLLinkElement-blob-url.html
index ba6e7eef397..a6002b78711 100644
--- a/Tests/LibWeb/Text/input/HTML/HTMLLinkElement-blob-url.html
+++ b/Tests/LibWeb/Text/input/HTML/HTMLLinkElement-blob-url.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div id="test-element">Test Element</div>
 <script>
diff --git a/Tests/LibWeb/Text/input/HTML/History-pushState-change-query.html b/Tests/LibWeb/Text/input/HTML/History-pushState-change-query.html
index b0154a9eb3e..2cc168888e5 100644
--- a/Tests/LibWeb/Text/input/HTML/History-pushState-change-query.html
+++ b/Tests/LibWeb/Text/input/HTML/History-pushState-change-query.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest((done) => {
diff --git a/Tests/LibWeb/Text/input/HTML/History-scrollRestoration.html b/Tests/LibWeb/Text/input/HTML/History-scrollRestoration.html
index 1408d0c12b8..9024905c216 100644
--- a/Tests/LibWeb/Text/input/HTML/History-scrollRestoration.html
+++ b/Tests/LibWeb/Text/input/HTML/History-scrollRestoration.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/HTML/Location-set-invalid-href-url.html b/Tests/LibWeb/Text/input/HTML/Location-set-invalid-href-url.html
index a9c61b0c675..b1e5291567b 100644
--- a/Tests/LibWeb/Text/input/HTML/Location-set-invalid-href-url.html
+++ b/Tests/LibWeb/Text/input/HTML/Location-set-invalid-href-url.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/HTML/ModuleLoading/import-inside-of-a-module.html b/Tests/LibWeb/Text/input/HTML/ModuleLoading/import-inside-of-a-module.html
index 60ff2e2e526..bbd605f450f 100644
--- a/Tests/LibWeb/Text/input/HTML/ModuleLoading/import-inside-of-a-module.html
+++ b/Tests/LibWeb/Text/input/HTML/ModuleLoading/import-inside-of-a-module.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../../include.js"></script>
 <script type="module">
     import m from "./import-in-a-module.js";
diff --git a/Tests/LibWeb/Text/input/HTML/Navigation-object-properties.html b/Tests/LibWeb/Text/input/HTML/Navigation-object-properties.html
index 9945bab0426..ded57e1a1d5 100644
--- a/Tests/LibWeb/Text/input/HTML/Navigation-object-properties.html
+++ b/Tests/LibWeb/Text/input/HTML/Navigation-object-properties.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/HTML/ShadowRealm-DOM-event.html b/Tests/LibWeb/Text/input/HTML/ShadowRealm-DOM-event.html
index 7a446b04596..a1bc9168313 100644
--- a/Tests/LibWeb/Text/input/HTML/ShadowRealm-DOM-event.html
+++ b/Tests/LibWeb/Text/input/HTML/ShadowRealm-DOM-event.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/HTML/ShadowRealm-importValue.html b/Tests/LibWeb/Text/input/HTML/ShadowRealm-importValue.html
index e94fde26521..c8fdd50b867 100644
--- a/Tests/LibWeb/Text/input/HTML/ShadowRealm-importValue.html
+++ b/Tests/LibWeb/Text/input/HTML/ShadowRealm-importValue.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest(async done => {
diff --git a/Tests/LibWeb/Text/input/HTML/ShadowRealm-in-ShadowRealm-evaluate-DOM-Event.html b/Tests/LibWeb/Text/input/HTML/ShadowRealm-in-ShadowRealm-evaluate-DOM-Event.html
index 3c6ac657408..2c7db936245 100644
--- a/Tests/LibWeb/Text/input/HTML/ShadowRealm-in-ShadowRealm-evaluate-DOM-Event.html
+++ b/Tests/LibWeb/Text/input/HTML/ShadowRealm-in-ShadowRealm-evaluate-DOM-Event.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     function shadowRealmEvalAsync(realm, asyncBody) {
diff --git a/Tests/LibWeb/Text/input/HTML/ShadowRealm-rejection.html b/Tests/LibWeb/Text/input/HTML/ShadowRealm-rejection.html
index 9f16c3decf2..68f0c4c34fa 100644
--- a/Tests/LibWeb/Text/input/HTML/ShadowRealm-rejection.html
+++ b/Tests/LibWeb/Text/input/HTML/ShadowRealm-rejection.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest(async done => {
diff --git a/Tests/LibWeb/Text/input/HTML/StructuredClone-array-buffer-views.html b/Tests/LibWeb/Text/input/HTML/StructuredClone-array-buffer-views.html
index 7615a1789be..27008a8fbe4 100644
--- a/Tests/LibWeb/Text/input/HTML/StructuredClone-array-buffer-views.html
+++ b/Tests/LibWeb/Text/input/HTML/StructuredClone-array-buffer-views.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     const TYPED_ARRAYS = [
diff --git a/Tests/LibWeb/Text/input/HTML/StructuredClone-object-primitives.html b/Tests/LibWeb/Text/input/HTML/StructuredClone-object-primitives.html
index 3bcafacd1c9..9d89981c65d 100644
--- a/Tests/LibWeb/Text/input/HTML/StructuredClone-object-primitives.html
+++ b/Tests/LibWeb/Text/input/HTML/StructuredClone-object-primitives.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/HTML/StructuredClone-primitives.html b/Tests/LibWeb/Text/input/HTML/StructuredClone-primitives.html
index cd7dc637aa8..15dd819271f 100644
--- a/Tests/LibWeb/Text/input/HTML/StructuredClone-primitives.html
+++ b/Tests/LibWeb/Text/input/HTML/StructuredClone-primitives.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/HTML/StructuredClone-serializable-FileList.html b/Tests/LibWeb/Text/input/HTML/StructuredClone-serializable-FileList.html
index 125d7744530..20c7dfa41a0 100644
--- a/Tests/LibWeb/Text/input/HTML/StructuredClone-serializable-FileList.html
+++ b/Tests/LibWeb/Text/input/HTML/StructuredClone-serializable-FileList.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <input id="input1" type="file" multiple />
 <script src="../include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/HTML/StructuredClone-serializable-objects.html b/Tests/LibWeb/Text/input/HTML/StructuredClone-serializable-objects.html
index 65d8856db97..f7aa39ef71d 100644
--- a/Tests/LibWeb/Text/input/HTML/StructuredClone-serializable-objects.html
+++ b/Tests/LibWeb/Text/input/HTML/StructuredClone-serializable-objects.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest(async done => {
diff --git a/Tests/LibWeb/Text/input/HTML/Window-close.html b/Tests/LibWeb/Text/input/HTML/Window-close.html
index d391adcd6d4..b4e8d97eb5f 100644
--- a/Tests/LibWeb/Text/input/HTML/Window-close.html
+++ b/Tests/LibWeb/Text/input/HTML/Window-close.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest(done => {
diff --git a/Tests/LibWeb/Text/input/HTML/Window-event-handler-in-detached-DOM.html b/Tests/LibWeb/Text/input/HTML/Window-event-handler-in-detached-DOM.html
index ef47c551554..df6adfb50cd 100644
--- a/Tests/LibWeb/Text/input/HTML/Window-event-handler-in-detached-DOM.html
+++ b/Tests/LibWeb/Text/input/HTML/Window-event-handler-in-detached-DOM.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/HTML/Window-find.html b/Tests/LibWeb/Text/input/HTML/Window-find.html
index 127e6c14cc9..91ac3bf039b 100644
--- a/Tests/LibWeb/Text/input/HTML/Window-find.html
+++ b/Tests/LibWeb/Text/input/HTML/Window-find.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div id="textContainer">
     <div style="display: none">This is hidden</div>
diff --git a/Tests/LibWeb/Text/input/HTML/Window-named-properties-elements.html b/Tests/LibWeb/Text/input/HTML/Window-named-properties-elements.html
index 4428576c3a3..2f17f7b47d4 100644
--- a/Tests/LibWeb/Text/input/HTML/Window-named-properties-elements.html
+++ b/Tests/LibWeb/Text/input/HTML/Window-named-properties-elements.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <embed name="m_bed" src="" type="">
 <img name="im_adge" src="">
diff --git a/Tests/LibWeb/Text/input/HTML/Window-named-properties-iframe.html b/Tests/LibWeb/Text/input/HTML/Window-named-properties-iframe.html
index d58d8edc6c1..68b8ce7b218 100644
--- a/Tests/LibWeb/Text/input/HTML/Window-named-properties-iframe.html
+++ b/Tests/LibWeb/Text/input/HTML/Window-named-properties-iframe.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <iframe name="framey" src=""></iframe>
 <iframe name=spices></iframe>
diff --git a/Tests/LibWeb/Text/input/HTML/Window-open-blob-url-without-blob-entry.html b/Tests/LibWeb/Text/input/HTML/Window-open-blob-url-without-blob-entry.html
index 3b5f9eb4dad..e9f61c06fd2 100644
--- a/Tests/LibWeb/Text/input/HTML/Window-open-blob-url-without-blob-entry.html
+++ b/Tests/LibWeb/Text/input/HTML/Window-open-blob-url-without-blob-entry.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/HTML/Window-open-empty-string.html b/Tests/LibWeb/Text/input/HTML/Window-open-empty-string.html
index c10b55a51bb..97860780e2a 100644
--- a/Tests/LibWeb/Text/input/HTML/Window-open-empty-string.html
+++ b/Tests/LibWeb/Text/input/HTML/Window-open-empty-string.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/HTML/Window-postMessage.html b/Tests/LibWeb/Text/input/HTML/Window-postMessage.html
index ec8f9608d6d..52ed9b57c1c 100644
--- a/Tests/LibWeb/Text/input/HTML/Window-postMessage.html
+++ b/Tests/LibWeb/Text/input/HTML/Window-postMessage.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <body>
 <iframe style="display: none" id="message-iframe" srcdoc="
 <body>
diff --git a/Tests/LibWeb/Text/input/HTML/Window-prototype.html b/Tests/LibWeb/Text/input/HTML/Window-prototype.html
index 5f35f3415dd..84c23107b8b 100644
--- a/Tests/LibWeb/Text/input/HTML/Window-prototype.html
+++ b/Tests/LibWeb/Text/input/HTML/Window-prototype.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/HTML/Window-set-properties.html b/Tests/LibWeb/Text/input/HTML/Window-set-properties.html
index 9637531eb7b..040ff150b91 100644
--- a/Tests/LibWeb/Text/input/HTML/Window-set-properties.html
+++ b/Tests/LibWeb/Text/input/HTML/Window-set-properties.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script id="__NEXT_DATA__"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/HTML/WindowOrWorkerGlobalScope-reportError.html b/Tests/LibWeb/Text/input/HTML/WindowOrWorkerGlobalScope-reportError.html
index 7021add9de5..9bf5732e725 100644
--- a/Tests/LibWeb/Text/input/HTML/WindowOrWorkerGlobalScope-reportError.html
+++ b/Tests/LibWeb/Text/input/HTML/WindowOrWorkerGlobalScope-reportError.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/HTML/WindowProxy-Get-after-detaching-from-browsing-context.html b/Tests/LibWeb/Text/input/HTML/WindowProxy-Get-after-detaching-from-browsing-context.html
index 08764cd4001..e8bd6b8bf18 100644
--- a/Tests/LibWeb/Text/input/HTML/WindowProxy-Get-after-detaching-from-browsing-context.html
+++ b/Tests/LibWeb/Text/input/HTML/WindowProxy-Get-after-detaching-from-browsing-context.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/HTML/a-element-set-protocol-on-href.html b/Tests/LibWeb/Text/input/HTML/a-element-set-protocol-on-href.html
index b0fc412cafd..f91eb74a1ea 100644
--- a/Tests/LibWeb/Text/input/HTML/a-element-set-protocol-on-href.html
+++ b/Tests/LibWeb/Text/input/HTML/a-element-set-protocol-on-href.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <a id="a" href="http://serenityos.org"></a>
 <script src="../include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/HTML/anchor-element-url-invalid-unicode-pathname.html b/Tests/LibWeb/Text/input/HTML/anchor-element-url-invalid-unicode-pathname.html
index d9724b3fa0d..c6372b2a560 100644
--- a/Tests/LibWeb/Text/input/HTML/anchor-element-url-invalid-unicode-pathname.html
+++ b/Tests/LibWeb/Text/input/HTML/anchor-element-url-invalid-unicode-pathname.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <a id="anchor" href="http://ladybird.org/foo%C2%91%91"></a>
 <script src="../include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/HTML/beforeunload.html b/Tests/LibWeb/Text/input/HTML/beforeunload.html
index 2d1e7428296..257c0ec6633 100644
--- a/Tests/LibWeb/Text/input/HTML/beforeunload.html
+++ b/Tests/LibWeb/Text/input/HTML/beforeunload.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest(done => {
diff --git a/Tests/LibWeb/Text/input/HTML/button-attributes.html b/Tests/LibWeb/Text/input/HTML/button-attributes.html
index bd7307e509a..82a61e07c82 100644
--- a/Tests/LibWeb/Text/input/HTML/button-attributes.html
+++ b/Tests/LibWeb/Text/input/HTML/button-attributes.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/HTML/canvas-getImageData-oblong.html b/Tests/LibWeb/Text/input/HTML/canvas-getImageData-oblong.html
index 5ba9b4e0c74..026fc00dba8 100644
--- a/Tests/LibWeb/Text/input/HTML/canvas-getImageData-oblong.html
+++ b/Tests/LibWeb/Text/input/HTML/canvas-getImageData-oblong.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <body><canvas id=c width=1 height=2></div>
 <script>
diff --git a/Tests/LibWeb/Text/input/HTML/canvas-putImageData-unpremultiplied.html b/Tests/LibWeb/Text/input/HTML/canvas-putImageData-unpremultiplied.html
index b4784b7d8e0..96822aa74f0 100644
--- a/Tests/LibWeb/Text/input/HTML/canvas-putImageData-unpremultiplied.html
+++ b/Tests/LibWeb/Text/input/HTML/canvas-putImageData-unpremultiplied.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <body><canvas id=c width=1 height=2></div>
 <script>
diff --git a/Tests/LibWeb/Text/input/HTML/cross-origin-WindowProxy-postMessage.html b/Tests/LibWeb/Text/input/HTML/cross-origin-WindowProxy-postMessage.html
index e0156fcf016..51e119ba75f 100644
--- a/Tests/LibWeb/Text/input/HTML/cross-origin-WindowProxy-postMessage.html
+++ b/Tests/LibWeb/Text/input/HTML/cross-origin-WindowProxy-postMessage.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <iframe id="i"></iframe>
 <script>
diff --git a/Tests/LibWeb/Text/input/HTML/custom-elements-throw-in-constructor.html b/Tests/LibWeb/Text/input/HTML/custom-elements-throw-in-constructor.html
index b32c1bffbc1..33ee7cf705f 100644
--- a/Tests/LibWeb/Text/input/HTML/custom-elements-throw-in-constructor.html
+++ b/Tests/LibWeb/Text/input/HTML/custom-elements-throw-in-constructor.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <test-element></test-element>
 <script src="../include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/HTML/data-transfer.html b/Tests/LibWeb/Text/input/HTML/data-transfer.html
index f3ed53f5134..88fa2068267 100644
--- a/Tests/LibWeb/Text/input/HTML/data-transfer.html
+++ b/Tests/LibWeb/Text/input/HTML/data-transfer.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest(async done => {
diff --git a/Tests/LibWeb/Text/input/HTML/datalist-element.html b/Tests/LibWeb/Text/input/HTML/datalist-element.html
index b25496e4484..6464a68e0e2 100644
--- a/Tests/LibWeb/Text/input/HTML/datalist-element.html
+++ b/Tests/LibWeb/Text/input/HTML/datalist-element.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/HTML/details-name.html b/Tests/LibWeb/Text/input/HTML/details-name.html
index 5805918a7ae..f4a8576e248 100644
--- a/Tests/LibWeb/Text/input/HTML/details-name.html
+++ b/Tests/LibWeb/Text/input/HTML/details-name.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <details id="details0" name="group1">
     <summary>Summary 0</summary>
     <span>Contents 0</span>
diff --git a/Tests/LibWeb/Text/input/HTML/document-named-shenanigans.html b/Tests/LibWeb/Text/input/HTML/document-named-shenanigans.html
index a61e6ab9953..59749025bf4 100644
--- a/Tests/LibWeb/Text/input/HTML/document-named-shenanigans.html
+++ b/Tests/LibWeb/Text/input/HTML/document-named-shenanigans.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     function go(tagName) {
diff --git a/Tests/LibWeb/Text/input/HTML/document-write-flush-character-insertions.html b/Tests/LibWeb/Text/input/HTML/document-write-flush-character-insertions.html
index 974279af3c8..97725ecdf20 100644
--- a/Tests/LibWeb/Text/input/HTML/document-write-flush-character-insertions.html
+++ b/Tests/LibWeb/Text/input/HTML/document-write-flush-character-insertions.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     document.write("PASS");
diff --git a/Tests/LibWeb/Text/input/HTML/drag-and-drop.html b/Tests/LibWeb/Text/input/HTML/drag-and-drop.html
index 5a40ec01005..f90ecaace75 100644
--- a/Tests/LibWeb/Text/input/HTML/drag-and-drop.html
+++ b/Tests/LibWeb/Text/input/HTML/drag-and-drop.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <div id="target" style="width: 200px; height: 200px"></div>
 <script src="../include.js"></script>
 <script type="text/javascript">
diff --git a/Tests/LibWeb/Text/input/HTML/form-element-enctype.html b/Tests/LibWeb/Text/input/HTML/form-element-enctype.html
index 23723113058..edb22e31a78 100644
--- a/Tests/LibWeb/Text/input/HTML/form-element-enctype.html
+++ b/Tests/LibWeb/Text/input/HTML/form-element-enctype.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <form id="testForm"></form>
 <script src="../include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/HTML/form-image-submission.html b/Tests/LibWeb/Text/input/HTML/form-image-submission.html
index c2a40f38a0e..f183e113eb0 100644
--- a/Tests/LibWeb/Text/input/HTML/form-image-submission.html
+++ b/Tests/LibWeb/Text/input/HTML/form-image-submission.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <head>
     <!--
         These style rules ensure the (x,y) coordinates clicked below are the same as the resulting
diff --git a/Tests/LibWeb/Text/input/HTML/form-implicit-submission.html b/Tests/LibWeb/Text/input/HTML/form-implicit-submission.html
index 90ab912e84a..9e22feac256 100644
--- a/Tests/LibWeb/Text/input/HTML/form-implicit-submission.html
+++ b/Tests/LibWeb/Text/input/HTML/form-implicit-submission.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <form id="defaultButton">
     <input />
     <button>PASS</button>
diff --git a/Tests/LibWeb/Text/input/HTML/get-innerHTML.html b/Tests/LibWeb/Text/input/HTML/get-innerHTML.html
index 57e285ed72c..8cf493aadfe 100644
--- a/Tests/LibWeb/Text/input/HTML/get-innerHTML.html
+++ b/Tests/LibWeb/Text/input/HTML/get-innerHTML.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <div id="id1">
   <ol reversed xml:myattribute></ol>
   <ol xmlns:somename></ol>
diff --git a/Tests/LibWeb/Text/input/HTML/href-invalid.html b/Tests/LibWeb/Text/input/HTML/href-invalid.html
index b4ec10d0feb..868461d054e 100644
--- a/Tests/LibWeb/Text/input/HTML/href-invalid.html
+++ b/Tests/LibWeb/Text/input/HTML/href-invalid.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/HTML/iframe-load-event-for-bad-xml.html b/Tests/LibWeb/Text/input/HTML/iframe-load-event-for-bad-xml.html
index 7f663a7182c..747bb148fae 100644
--- a/Tests/LibWeb/Text/input/HTML/iframe-load-event-for-bad-xml.html
+++ b/Tests/LibWeb/Text/input/HTML/iframe-load-event-for-bad-xml.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <iframe id="i1"></iframe>
 <script src="../include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/HTML/iframe-reload-on-src-or-srcdoc-change.html b/Tests/LibWeb/Text/input/HTML/iframe-reload-on-src-or-srcdoc-change.html
index a514730b9b4..501b4b42736 100644
--- a/Tests/LibWeb/Text/input/HTML/iframe-reload-on-src-or-srcdoc-change.html
+++ b/Tests/LibWeb/Text/input/HTML/iframe-reload-on-src-or-srcdoc-change.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <iframe id="test-iframe"></iframe>
 <script src="../include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/HTML/image-bitmap-from-invalid-types-no-crash.html b/Tests/LibWeb/Text/input/HTML/image-bitmap-from-invalid-types-no-crash.html
index 7c5ba4d8418..80430362a5a 100644
--- a/Tests/LibWeb/Text/input/HTML/image-bitmap-from-invalid-types-no-crash.html
+++ b/Tests/LibWeb/Text/input/HTML/image-bitmap-from-invalid-types-no-crash.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     let canvas = document.createElement("canvas");
diff --git a/Tests/LibWeb/Text/input/HTML/img-metrics-in-load-event-handlers.html b/Tests/LibWeb/Text/input/HTML/img-metrics-in-load-event-handlers.html
index 910b189d7ac..1896e94898b 100644
--- a/Tests/LibWeb/Text/input/HTML/img-metrics-in-load-event-handlers.html
+++ b/Tests/LibWeb/Text/input/HTML/img-metrics-in-load-event-handlers.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest((done) => {
diff --git a/Tests/LibWeb/Text/input/HTML/img-src-in-innerHTML-crash.html b/Tests/LibWeb/Text/input/HTML/img-src-in-innerHTML-crash.html
index 76bc46cfd04..c352258832e 100644
--- a/Tests/LibWeb/Text/input/HTML/img-src-in-innerHTML-crash.html
+++ b/Tests/LibWeb/Text/input/HTML/img-src-in-innerHTML-crash.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/HTML/link-element-username-password-percent-encoded.html b/Tests/LibWeb/Text/input/HTML/link-element-username-password-percent-encoded.html
index cc726c853dd..7ae595f963c 100644
--- a/Tests/LibWeb/Text/input/HTML/link-element-username-password-percent-encoded.html
+++ b/Tests/LibWeb/Text/input/HTML/link-element-username-password-percent-encoded.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <a id="username-and-password" href="http://user%20name:pa%40ss%3Aword@www.ladybird.org"></a>
 <script src="../include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/HTML/local-storage-usage-after-nav.html b/Tests/LibWeb/Text/input/HTML/local-storage-usage-after-nav.html
index 5038ee36485..e9734bd8a59 100644
--- a/Tests/LibWeb/Text/input/HTML/local-storage-usage-after-nav.html
+++ b/Tests/LibWeb/Text/input/HTML/local-storage-usage-after-nav.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <iframe id="frame" src="../../data/local-storage-iframe.html"></iframe>
 <script src="../include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/HTML/map-element.html b/Tests/LibWeb/Text/input/HTML/map-element.html
index d424a8924d4..af8987308de 100644
--- a/Tests/LibWeb/Text/input/HTML/map-element.html
+++ b/Tests/LibWeb/Text/input/HTML/map-element.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/HTML/maxed-out-dimension-value.html b/Tests/LibWeb/Text/input/HTML/maxed-out-dimension-value.html
index 9a5709f3277..67d7271e8f8 100644
--- a/Tests/LibWeb/Text/input/HTML/maxed-out-dimension-value.html
+++ b/Tests/LibWeb/Text/input/HTML/maxed-out-dimension-value.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <img height="2147483647">
 <script src="../include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/HTML/navigator-beacon.html b/Tests/LibWeb/Text/input/HTML/navigator-beacon.html
index c72b6f78a14..71d26399d86 100644
--- a/Tests/LibWeb/Text/input/HTML/navigator-beacon.html
+++ b/Tests/LibWeb/Text/input/HTML/navigator-beacon.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/HTML/onreadystatechange.html b/Tests/LibWeb/Text/input/HTML/onreadystatechange.html
index d8687b84de5..88cfea03d62 100644
--- a/Tests/LibWeb/Text/input/HTML/onreadystatechange.html
+++ b/Tests/LibWeb/Text/input/HTML/onreadystatechange.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     let readyStates = []
diff --git a/Tests/LibWeb/Text/input/HTML/outerHTML.html b/Tests/LibWeb/Text/input/HTML/outerHTML.html
index 8b56d5aca4b..de1ac82757d 100644
--- a/Tests/LibWeb/Text/input/HTML/outerHTML.html
+++ b/Tests/LibWeb/Text/input/HTML/outerHTML.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div id="foo"><b>hello students</b></div>
 <script>
diff --git a/Tests/LibWeb/Text/input/HTML/pageshow-event-istrusted.html b/Tests/LibWeb/Text/input/HTML/pageshow-event-istrusted.html
index bb8a89c344e..53445740c4a 100644
--- a/Tests/LibWeb/Text/input/HTML/pageshow-event-istrusted.html
+++ b/Tests/LibWeb/Text/input/HTML/pageshow-event-istrusted.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <iframe id="i"></iframe>
 <script>
diff --git a/Tests/LibWeb/Text/input/HTML/place-items-shorthand.html b/Tests/LibWeb/Text/input/HTML/place-items-shorthand.html
index 47d1c6d271a..cfa6570b6ca 100644
--- a/Tests/LibWeb/Text/input/HTML/place-items-shorthand.html
+++ b/Tests/LibWeb/Text/input/HTML/place-items-shorthand.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/HTML/png-without-IDAT-should-still-load.html b/Tests/LibWeb/Text/input/HTML/png-without-IDAT-should-still-load.html
index 7646e21153b..f9fd8765fea 100644
--- a/Tests/LibWeb/Text/input/HTML/png-without-IDAT-should-still-load.html
+++ b/Tests/LibWeb/Text/input/HTML/png-without-IDAT-should-still-load.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest(done => {
diff --git a/Tests/LibWeb/Text/input/HTML/pre-width.html b/Tests/LibWeb/Text/input/HTML/pre-width.html
index e2598da8cf7..d3fc9c6025b 100644
--- a/Tests/LibWeb/Text/input/HTML/pre-width.html
+++ b/Tests/LibWeb/Text/input/HTML/pre-width.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/HTML/pushState-navigation-event.html b/Tests/LibWeb/Text/input/HTML/pushState-navigation-event.html
index abf27afb7e8..104014d95d9 100644
--- a/Tests/LibWeb/Text/input/HTML/pushState-navigation-event.html
+++ b/Tests/LibWeb/Text/input/HTML/pushState-navigation-event.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest((done) => {
diff --git a/Tests/LibWeb/Text/input/HTML/requestAnimationFrame-gc.html b/Tests/LibWeb/Text/input/HTML/requestAnimationFrame-gc.html
index 0a1b63423bf..9e2cae0337e 100644
--- a/Tests/LibWeb/Text/input/HTML/requestAnimationFrame-gc.html
+++ b/Tests/LibWeb/Text/input/HTML/requestAnimationFrame-gc.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest((done) => {
diff --git a/Tests/LibWeb/Text/input/HTML/requestAnimationFrame-sequential.html b/Tests/LibWeb/Text/input/HTML/requestAnimationFrame-sequential.html
index 88a253b0f97..a0f00c20588 100644
--- a/Tests/LibWeb/Text/input/HTML/requestAnimationFrame-sequential.html
+++ b/Tests/LibWeb/Text/input/HTML/requestAnimationFrame-sequential.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     var rafIds = [];
diff --git a/Tests/LibWeb/Text/input/HTML/select-index-is-in-tree-order.html b/Tests/LibWeb/Text/input/HTML/select-index-is-in-tree-order.html
index 88188698ec3..69b4b72f38a 100644
--- a/Tests/LibWeb/Text/input/HTML/select-index-is-in-tree-order.html
+++ b/Tests/LibWeb/Text/input/HTML/select-index-is-in-tree-order.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <select id="test-select">
     <option value="0" selected>Option 0</option>
     <optgroup label="Group 1">
diff --git a/Tests/LibWeb/Text/input/HTML/select-setValue-after-construction.html b/Tests/LibWeb/Text/input/HTML/select-setValue-after-construction.html
index 2b8a71f958b..291d9f98077 100644
--- a/Tests/LibWeb/Text/input/HTML/select-setValue-after-construction.html
+++ b/Tests/LibWeb/Text/input/HTML/select-setValue-after-construction.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/HTML/set-innerHTML-details.html b/Tests/LibWeb/Text/input/HTML/set-innerHTML-details.html
index 921b0c7b005..86ee8c7c974 100644
--- a/Tests/LibWeb/Text/input/HTML/set-innerHTML-details.html
+++ b/Tests/LibWeb/Text/input/HTML/set-innerHTML-details.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <div id=test></div>
 <script src="../include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/HTML/set-innerHTML-input.html b/Tests/LibWeb/Text/input/HTML/set-innerHTML-input.html
index 32e9c29681b..646f753e5b9 100644
--- a/Tests/LibWeb/Text/input/HTML/set-innerHTML-input.html
+++ b/Tests/LibWeb/Text/input/HTML/set-innerHTML-input.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <div id=test></div>
 <script src="../include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/HTML/set-innerHTML-inside-iframe-srcdoc-document.html b/Tests/LibWeb/Text/input/HTML/set-innerHTML-inside-iframe-srcdoc-document.html
index 5a979281ec0..61213a60790 100644
--- a/Tests/LibWeb/Text/input/HTML/set-innerHTML-inside-iframe-srcdoc-document.html
+++ b/Tests/LibWeb/Text/input/HTML/set-innerHTML-inside-iframe-srcdoc-document.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <iframe id="ifr" srcdoc=""></iframe>
 <script src="../include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/HTML/set-innerHTML-textarea.html b/Tests/LibWeb/Text/input/HTML/set-innerHTML-textarea.html
index a9195fe0ed0..f1f8a2ed1fd 100644
--- a/Tests/LibWeb/Text/input/HTML/set-innerHTML-textarea.html
+++ b/Tests/LibWeb/Text/input/HTML/set-innerHTML-textarea.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <div id=test></div>
 <script src="../include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/HTML/set-innerHTML-with-script.html b/Tests/LibWeb/Text/input/HTML/set-innerHTML-with-script.html
index 46301fc4335..6ed6fd2a886 100644
--- a/Tests/LibWeb/Text/input/HTML/set-innerHTML-with-script.html
+++ b/Tests/LibWeb/Text/input/HTML/set-innerHTML-with-script.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div id=container></div>
 <script type="text/javascript">
diff --git a/Tests/LibWeb/Text/input/HTML/set-innerText.html b/Tests/LibWeb/Text/input/HTML/set-innerText.html
index a8b568fb228..0913d18d888 100644
--- a/Tests/LibWeb/Text/input/HTML/set-innerText.html
+++ b/Tests/LibWeb/Text/input/HTML/set-innerText.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/HTML/set-outerHTML.html b/Tests/LibWeb/Text/input/HTML/set-outerHTML.html
index 4a5c847c947..80fea90a804 100644
--- a/Tests/LibWeb/Text/input/HTML/set-outerHTML.html
+++ b/Tests/LibWeb/Text/input/HTML/set-outerHTML.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div id="oldBox"><p>A box.</p></div>
 <script>
diff --git a/Tests/LibWeb/Text/input/HTML/shadow-realm-async-evaluate.html b/Tests/LibWeb/Text/input/HTML/shadow-realm-async-evaluate.html
index 46e92a937c4..903d693405b 100644
--- a/Tests/LibWeb/Text/input/HTML/shadow-realm-async-evaluate.html
+++ b/Tests/LibWeb/Text/input/HTML/shadow-realm-async-evaluate.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/HTML/shadow-realm-btoa.html b/Tests/LibWeb/Text/input/HTML/shadow-realm-btoa.html
index 0d7375c746b..946a5de8fdb 100644
--- a/Tests/LibWeb/Text/input/HTML/shadow-realm-btoa.html
+++ b/Tests/LibWeb/Text/input/HTML/shadow-realm-btoa.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/HTML/shadow-realm-sync-evaluate.html b/Tests/LibWeb/Text/input/HTML/shadow-realm-sync-evaluate.html
index a1cf3f1fa3d..3798e3673e5 100644
--- a/Tests/LibWeb/Text/input/HTML/shadow-realm-sync-evaluate.html
+++ b/Tests/LibWeb/Text/input/HTML/shadow-realm-sync-evaluate.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/HTML/shadow-realm-url.html b/Tests/LibWeb/Text/input/HTML/shadow-realm-url.html
index 3db5b42ab33..39f8ec4ba4c 100644
--- a/Tests/LibWeb/Text/input/HTML/shadow-realm-url.html
+++ b/Tests/LibWeb/Text/input/HTML/shadow-realm-url.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/HTML/short-legacy-color-value.html b/Tests/LibWeb/Text/input/HTML/short-legacy-color-value.html
index d37468df8ca..d2df992238c 100644
--- a/Tests/LibWeb/Text/input/HTML/short-legacy-color-value.html
+++ b/Tests/LibWeb/Text/input/HTML/short-legacy-color-value.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <body bgcolor="foo">
 <script>
diff --git a/Tests/LibWeb/Text/input/HTML/submit-button-click-when-disabled.html b/Tests/LibWeb/Text/input/HTML/submit-button-click-when-disabled.html
index 23068912be9..917acf5e862 100644
--- a/Tests/LibWeb/Text/input/HTML/submit-button-click-when-disabled.html
+++ b/Tests/LibWeb/Text/input/HTML/submit-button-click-when-disabled.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <form id="theForm" style="display:none"><button id="theButton" type="submit" disabled></button></form>
 <script src="../include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/HTML/table-cellpadding.html b/Tests/LibWeb/Text/input/HTML/table-cellpadding.html
index 3e3a0d15bd7..afbd57401d3 100644
--- a/Tests/LibWeb/Text/input/HTML/table-cellpadding.html
+++ b/Tests/LibWeb/Text/input/HTML/table-cellpadding.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <table id="table"><td id="td"></td></table>
 <script>
diff --git a/Tests/LibWeb/Text/input/HTML/tbody-insert-row.html b/Tests/LibWeb/Text/input/HTML/tbody-insert-row.html
index e0ca77388c9..4de40d24aa2 100644
--- a/Tests/LibWeb/Text/input/HTML/tbody-insert-row.html
+++ b/Tests/LibWeb/Text/input/HTML/tbody-insert-row.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <table><tbody id="tbody"><tr></tr></tbody></table>
 <script src="../include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/IntersectionObserver/implicit-root-after-originating-iframe-is-removed-from-dom.html b/Tests/LibWeb/Text/input/IntersectionObserver/implicit-root-after-originating-iframe-is-removed-from-dom.html
index ace20938914..924d20e28d9 100644
--- a/Tests/LibWeb/Text/input/IntersectionObserver/implicit-root-after-originating-iframe-is-removed-from-dom.html
+++ b/Tests/LibWeb/Text/input/IntersectionObserver/implicit-root-after-originating-iframe-is-removed-from-dom.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <body>
 <iframe></iframe>
 <script src="../include.js"></script>
diff --git a/Tests/LibWeb/Text/input/IntersectionObserver/unobserve-element-without-matching-observe.html b/Tests/LibWeb/Text/input/IntersectionObserver/unobserve-element-without-matching-observe.html
index 39b64052a6a..870eb889b74 100644
--- a/Tests/LibWeb/Text/input/IntersectionObserver/unobserve-element-without-matching-observe.html
+++ b/Tests/LibWeb/Text/input/IntersectionObserver/unobserve-element-without-matching-observe.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <body>
 <script src="../include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/Messaging/MessagePort-start-after-close.html b/Tests/LibWeb/Text/input/Messaging/MessagePort-start-after-close.html
index 4c36d3af5ee..d7a8f3635b5 100644
--- a/Tests/LibWeb/Text/input/Messaging/MessagePort-start-after-close.html
+++ b/Tests/LibWeb/Text/input/Messaging/MessagePort-start-after-close.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/Messaging/Messaging-basic-channel.html b/Tests/LibWeb/Text/input/Messaging/Messaging-basic-channel.html
index 99c30baf973..f871b7146b7 100644
--- a/Tests/LibWeb/Text/input/Messaging/Messaging-basic-channel.html
+++ b/Tests/LibWeb/Text/input/Messaging/Messaging-basic-channel.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest(done => {
diff --git a/Tests/LibWeb/Text/input/Messaging/Messaging-post-channel-over-channel.html b/Tests/LibWeb/Text/input/Messaging/Messaging-post-channel-over-channel.html
index bc958f45665..ed1cd00137d 100644
--- a/Tests/LibWeb/Text/input/Messaging/Messaging-post-channel-over-channel.html
+++ b/Tests/LibWeb/Text/input/Messaging/Messaging-post-channel-over-channel.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest(done => {
diff --git a/Tests/LibWeb/Text/input/MutationObserver/removing-a-node.html b/Tests/LibWeb/Text/input/MutationObserver/removing-a-node.html
index 6a8324c04f0..8743ba0d8e6 100644
--- a/Tests/LibWeb/Text/input/MutationObserver/removing-a-node.html
+++ b/Tests/LibWeb/Text/input/MutationObserver/removing-a-node.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <body>
 <script src="../include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/PerformanceObserver/PerformanceObserver-supportedEntryTypes.html b/Tests/LibWeb/Text/input/PerformanceObserver/PerformanceObserver-supportedEntryTypes.html
index 662fd94df66..1805d9c4fdd 100644
--- a/Tests/LibWeb/Text/input/PerformanceObserver/PerformanceObserver-supportedEntryTypes.html
+++ b/Tests/LibWeb/Text/input/PerformanceObserver/PerformanceObserver-supportedEntryTypes.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/PerformanceObserver/PerformanceObserver_basic.html b/Tests/LibWeb/Text/input/PerformanceObserver/PerformanceObserver_basic.html
index db9001a9cfc..5b84c78c130 100644
--- a/Tests/LibWeb/Text/input/PerformanceObserver/PerformanceObserver_basic.html
+++ b/Tests/LibWeb/Text/input/PerformanceObserver/PerformanceObserver_basic.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     const bufferedMessages = [];
diff --git a/Tests/LibWeb/Text/input/ProcessingInstruction-cloneNode.html b/Tests/LibWeb/Text/input/ProcessingInstruction-cloneNode.html
index 63fd7bfd684..196ad5bebc7 100644
--- a/Tests/LibWeb/Text/input/ProcessingInstruction-cloneNode.html
+++ b/Tests/LibWeb/Text/input/ProcessingInstruction-cloneNode.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <script>
   test(() => {
diff --git a/Tests/LibWeb/Text/input/SVG/a-element-prototype.html b/Tests/LibWeb/Text/input/SVG/a-element-prototype.html
index fba38cfa468..e5b82ae5930 100644
--- a/Tests/LibWeb/Text/input/SVG/a-element-prototype.html
+++ b/Tests/LibWeb/Text/input/SVG/a-element-prototype.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/SVG/svg-circle-detached.html b/Tests/LibWeb/Text/input/SVG/svg-circle-detached.html
index 40feeb65175..1e7d1ab6b8c 100644
--- a/Tests/LibWeb/Text/input/SVG/svg-circle-detached.html
+++ b/Tests/LibWeb/Text/input/SVG/svg-circle-detached.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/SVG/svg-className-attribute.html b/Tests/LibWeb/Text/input/SVG/svg-className-attribute.html
index 9d79807ba59..ca2a0b7304d 100644
--- a/Tests/LibWeb/Text/input/SVG/svg-className-attribute.html
+++ b/Tests/LibWeb/Text/input/SVG/svg-className-attribute.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <svg xmlns="http://www.w3.org/2000/svg" id="svg-element" class="demo class"></svg>
 <script>
diff --git a/Tests/LibWeb/Text/input/SVG/svg-element-proto.html b/Tests/LibWeb/Text/input/SVG/svg-element-proto.html
index f4680826e6f..7c5eb1ae61c 100644
--- a/Tests/LibWeb/Text/input/SVG/svg-element-proto.html
+++ b/Tests/LibWeb/Text/input/SVG/svg-element-proto.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/SVG/svg-href-qualified-name.html b/Tests/LibWeb/Text/input/SVG/svg-href-qualified-name.html
index 9a93cee23cc..870386acfc5 100644
--- a/Tests/LibWeb/Text/input/SVG/svg-href-qualified-name.html
+++ b/Tests/LibWeb/Text/input/SVG/svg-href-qualified-name.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <svg xmlns="http://www.w3.org/2000/svg">
     <script id="explicit-xlink-href" xlink:href="test"></script>
diff --git a/Tests/LibWeb/Text/input/SVG/svg-href.html b/Tests/LibWeb/Text/input/SVG/svg-href.html
index d957bf6a98a..8e09fc4eeec 100644
--- a/Tests/LibWeb/Text/input/SVG/svg-href.html
+++ b/Tests/LibWeb/Text/input/SVG/svg-href.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <svg xmlns="http://www.w3.org/2000/svg" id="svg-element">
     <use class="no-xlink-href"></use>
diff --git a/Tests/LibWeb/Text/input/SVG/svg-ownerSVGElement-attribute.html b/Tests/LibWeb/Text/input/SVG/svg-ownerSVGElement-attribute.html
index 0748662ba08..779bb091ddc 100644
--- a/Tests/LibWeb/Text/input/SVG/svg-ownerSVGElement-attribute.html
+++ b/Tests/LibWeb/Text/input/SVG/svg-ownerSVGElement-attribute.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <svg xmlns="http://www.w3.org/2000/svg" id="svg-element">
     <linearGradient id="linear-gradient-element" />
diff --git a/Tests/LibWeb/Text/input/SVG/svg-script-element.html b/Tests/LibWeb/Text/input/SVG/svg-script-element.html
index ae57ff3ad3c..d82ce320b79 100644
--- a/Tests/LibWeb/Text/input/SVG/svg-script-element.html
+++ b/Tests/LibWeb/Text/input/SVG/svg-script-element.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <svg xmlns="http://www.w3.org/2000/svg">
     <script id="svg-script-element">
diff --git a/Tests/LibWeb/Text/input/SVG/svg-svg-getElementById.html b/Tests/LibWeb/Text/input/SVG/svg-svg-getElementById.html
index 0a072ce46f1..5e27b3cff6e 100644
--- a/Tests/LibWeb/Text/input/SVG/svg-svg-getElementById.html
+++ b/Tests/LibWeb/Text/input/SVG/svg-svg-getElementById.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <svg id="svgRoot"></svg>
 <script>
diff --git a/Tests/LibWeb/Text/input/SVG/svg-viewBox-attribute.html b/Tests/LibWeb/Text/input/SVG/svg-viewBox-attribute.html
index d5b2424d021..6f18fe20eb8 100644
--- a/Tests/LibWeb/Text/input/SVG/svg-viewBox-attribute.html
+++ b/Tests/LibWeb/Text/input/SVG/svg-viewBox-attribute.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <svg xmlns="http://www.w3.org/2000/svg" style="display: none" id="svg-element"></svg>
 <script>
diff --git a/Tests/LibWeb/Text/input/SVG/svg-viewbox-zero-height.html b/Tests/LibWeb/Text/input/SVG/svg-viewbox-zero-height.html
index 618fa25327b..ff4f0a1a792 100644
--- a/Tests/LibWeb/Text/input/SVG/svg-viewbox-zero-height.html
+++ b/Tests/LibWeb/Text/input/SVG/svg-viewbox-zero-height.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <svg xmlns="http://www.w3.org/2000/svg" id="svg-element"></svg>
 <script>
diff --git a/Tests/LibWeb/Text/input/Selection-setBaseAndExtent-without-common-root.html b/Tests/LibWeb/Text/input/Selection-setBaseAndExtent-without-common-root.html
index 2c47b0f7c99..5d5a86f219f 100644
--- a/Tests/LibWeb/Text/input/Selection-setBaseAndExtent-without-common-root.html
+++ b/Tests/LibWeb/Text/input/Selection-setBaseAndExtent-without-common-root.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <body>
 <script src="include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/ShadowDOM/css-hover-shadow-dom.html b/Tests/LibWeb/Text/input/ShadowDOM/css-hover-shadow-dom.html
index ce96dd80ac3..346bf3ad9c4 100644
--- a/Tests/LibWeb/Text/input/ShadowDOM/css-hover-shadow-dom.html
+++ b/Tests/LibWeb/Text/input/ShadowDOM/css-hover-shadow-dom.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <style>
 #myShadowHost:hover {
     background: green;
diff --git a/Tests/LibWeb/Text/input/ShadowDOM/css-media-queries.html b/Tests/LibWeb/Text/input/ShadowDOM/css-media-queries.html
index eefe5e2186d..e3900c943e3 100644
--- a/Tests/LibWeb/Text/input/ShadowDOM/css-media-queries.html
+++ b/Tests/LibWeb/Text/input/ShadowDOM/css-media-queries.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <div id="myShadowHost">
 <template shadowrootmode="open">
 <style>
diff --git a/Tests/LibWeb/Text/input/ShadowDOM/css-variable-inheritance-across-shadow-boundary.html b/Tests/LibWeb/Text/input/ShadowDOM/css-variable-inheritance-across-shadow-boundary.html
index 236dbb4f6de..a9725fb5373 100644
--- a/Tests/LibWeb/Text/input/ShadowDOM/css-variable-inheritance-across-shadow-boundary.html
+++ b/Tests/LibWeb/Text/input/ShadowDOM/css-variable-inheritance-across-shadow-boundary.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <style>
 :root {
     --foo: green;
diff --git a/Tests/LibWeb/Text/input/ShadowDOM/declarative-basic.html b/Tests/LibWeb/Text/input/ShadowDOM/declarative-basic.html
index 83f2ca3483b..7418dd46d14 100644
--- a/Tests/LibWeb/Text/input/ShadowDOM/declarative-basic.html
+++ b/Tests/LibWeb/Text/input/ShadowDOM/declarative-basic.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <div id="basicOpen">
 <template shadowrootmode="open">open</template>
 </div>
diff --git a/Tests/LibWeb/Text/input/ShadowDOM/remove-style-element-inside-shadow-tree.html b/Tests/LibWeb/Text/input/ShadowDOM/remove-style-element-inside-shadow-tree.html
index c5642083f25..b9e676360d2 100644
--- a/Tests/LibWeb/Text/input/ShadowDOM/remove-style-element-inside-shadow-tree.html
+++ b/Tests/LibWeb/Text/input/ShadowDOM/remove-style-element-inside-shadow-tree.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <div id=foo>
 <template shadowrootmode="open">
 <style>
diff --git a/Tests/LibWeb/Text/input/ShadowDOM/replace-declarative-shadow-root-with-style-sheet.html b/Tests/LibWeb/Text/input/ShadowDOM/replace-declarative-shadow-root-with-style-sheet.html
index e9e64053ab5..daac13dd783 100644
--- a/Tests/LibWeb/Text/input/ShadowDOM/replace-declarative-shadow-root-with-style-sheet.html
+++ b/Tests/LibWeb/Text/input/ShadowDOM/replace-declarative-shadow-root-with-style-sheet.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <div id="hmmst"><template shadowrootmode="open"><div><style></style></div></template></div>
 <script src="../include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/Streams/ByteLengthQueuingStrategy-enqueue-desired-size.html b/Tests/LibWeb/Text/input/Streams/ByteLengthQueuingStrategy-enqueue-desired-size.html
index 2bb07ecc450..5ac76c8c6a5 100644
--- a/Tests/LibWeb/Text/input/Streams/ByteLengthQueuingStrategy-enqueue-desired-size.html
+++ b/Tests/LibWeb/Text/input/Streams/ByteLengthQueuingStrategy-enqueue-desired-size.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/Streams/CountQueuingStrategy-enqueue-desired-size.html b/Tests/LibWeb/Text/input/Streams/CountQueuingStrategy-enqueue-desired-size.html
index 925fb17e05a..7ca48b348ab 100644
--- a/Tests/LibWeb/Text/input/Streams/CountQueuingStrategy-enqueue-desired-size.html
+++ b/Tests/LibWeb/Text/input/Streams/CountQueuingStrategy-enqueue-desired-size.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/Streams/QueuingStrategy-high-water-mark.html b/Tests/LibWeb/Text/input/Streams/QueuingStrategy-high-water-mark.html
index 13fd651ac93..4652781b49f 100644
--- a/Tests/LibWeb/Text/input/Streams/QueuingStrategy-high-water-mark.html
+++ b/Tests/LibWeb/Text/input/Streams/QueuingStrategy-high-water-mark.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/Streams/QueuingStrategy-same-instance.html b/Tests/LibWeb/Text/input/Streams/QueuingStrategy-same-instance.html
index 0eb995bb6c5..a98814f65b5 100644
--- a/Tests/LibWeb/Text/input/Streams/QueuingStrategy-same-instance.html
+++ b/Tests/LibWeb/Text/input/Streams/QueuingStrategy-same-instance.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/Streams/ReadableByteStream-byob-tee.html b/Tests/LibWeb/Text/input/Streams/ReadableByteStream-byob-tee.html
index 333f910e8a9..500cdf24312 100644
--- a/Tests/LibWeb/Text/input/Streams/ReadableByteStream-byob-tee.html
+++ b/Tests/LibWeb/Text/input/Streams/ReadableByteStream-byob-tee.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     const CHUNK1 = "abcdefghijklmnopqrstuvwxyz";
diff --git a/Tests/LibWeb/Text/input/Streams/ReadableByteStream-default-tee.html b/Tests/LibWeb/Text/input/Streams/ReadableByteStream-default-tee.html
index b425850b837..37d3eef6d9f 100644
--- a/Tests/LibWeb/Text/input/Streams/ReadableByteStream-default-tee.html
+++ b/Tests/LibWeb/Text/input/Streams/ReadableByteStream-default-tee.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     const CHUNK1 = "abcdefghijklmnopqrstuvwxyz";
diff --git a/Tests/LibWeb/Text/input/Streams/ReadableByteStream-enqueue-respond.html b/Tests/LibWeb/Text/input/Streams/ReadableByteStream-enqueue-respond.html
index 3d586682370..f572d71a2e1 100644
--- a/Tests/LibWeb/Text/input/Streams/ReadableByteStream-enqueue-respond.html
+++ b/Tests/LibWeb/Text/input/Streams/ReadableByteStream-enqueue-respond.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
 function makeReadableByteStream() {
diff --git a/Tests/LibWeb/Text/input/Streams/ReadableStream-autoAllocateChunkSize-constructor.html b/Tests/LibWeb/Text/input/Streams/ReadableStream-autoAllocateChunkSize-constructor.html
index 73843944f94..51d6781ce68 100644
--- a/Tests/LibWeb/Text/input/Streams/ReadableStream-autoAllocateChunkSize-constructor.html
+++ b/Tests/LibWeb/Text/input/Streams/ReadableStream-autoAllocateChunkSize-constructor.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/Streams/ReadableStream-can-cancel.html b/Tests/LibWeb/Text/input/Streams/ReadableStream-can-cancel.html
index fee2c435b77..a7674aa6cd4 100644
--- a/Tests/LibWeb/Text/input/Streams/ReadableStream-can-cancel.html
+++ b/Tests/LibWeb/Text/input/Streams/ReadableStream-can-cancel.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     function testReadableStreamCancellation() {
diff --git a/Tests/LibWeb/Text/input/Streams/ReadableStream-default-tee.html b/Tests/LibWeb/Text/input/Streams/ReadableStream-default-tee.html
index 01eca132f26..b3286ffa94e 100644
--- a/Tests/LibWeb/Text/input/Streams/ReadableStream-default-tee.html
+++ b/Tests/LibWeb/Text/input/Streams/ReadableStream-default-tee.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     const CHUNK1 = "abcdefghijklmnopqrstuvwxyz";
diff --git a/Tests/LibWeb/Text/input/Streams/ReadableStream-from-asyncIterator.html b/Tests/LibWeb/Text/input/Streams/ReadableStream-from-asyncIterator.html
index 65cf4a257ab..453b68c1b6b 100644
--- a/Tests/LibWeb/Text/input/Streams/ReadableStream-from-asyncIterator.html
+++ b/Tests/LibWeb/Text/input/Streams/ReadableStream-from-asyncIterator.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     async function* asyncGenerator() {
diff --git a/Tests/LibWeb/Text/input/Streams/ReadableStream-pipeThrough-cannot-pipe-locked-stream.html b/Tests/LibWeb/Text/input/Streams/ReadableStream-pipeThrough-cannot-pipe-locked-stream.html
index 8069e28e638..77188885b9c 100644
--- a/Tests/LibWeb/Text/input/Streams/ReadableStream-pipeThrough-cannot-pipe-locked-stream.html
+++ b/Tests/LibWeb/Text/input/Streams/ReadableStream-pipeThrough-cannot-pipe-locked-stream.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest(done => {
diff --git a/Tests/LibWeb/Text/input/Streams/ReadableStream-pipeThrough-cannot-pipe-to-locked-stream.html b/Tests/LibWeb/Text/input/Streams/ReadableStream-pipeThrough-cannot-pipe-to-locked-stream.html
index 9dd1d12bcd9..47c4f3cf3dd 100644
--- a/Tests/LibWeb/Text/input/Streams/ReadableStream-pipeThrough-cannot-pipe-to-locked-stream.html
+++ b/Tests/LibWeb/Text/input/Streams/ReadableStream-pipeThrough-cannot-pipe-to-locked-stream.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest(done => {
diff --git a/Tests/LibWeb/Text/input/Streams/ReadableStream-pipeThrough.html b/Tests/LibWeb/Text/input/Streams/ReadableStream-pipeThrough.html
index d22944c7acb..0cc433d8a32 100644
--- a/Tests/LibWeb/Text/input/Streams/ReadableStream-pipeThrough.html
+++ b/Tests/LibWeb/Text/input/Streams/ReadableStream-pipeThrough.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     const CHUNK1 =  "well,";
diff --git a/Tests/LibWeb/Text/input/Streams/ReadableStream-pipeTo-Writer-close-callback-called.html b/Tests/LibWeb/Text/input/Streams/ReadableStream-pipeTo-Writer-close-callback-called.html
index b6cd67d13ed..59d063b5c35 100644
--- a/Tests/LibWeb/Text/input/Streams/ReadableStream-pipeTo-Writer-close-callback-called.html
+++ b/Tests/LibWeb/Text/input/Streams/ReadableStream-pipeTo-Writer-close-callback-called.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest(done => {
diff --git a/Tests/LibWeb/Text/input/Streams/ReadableStream-pipeTo-cannot-pipe-locked-stream.html b/Tests/LibWeb/Text/input/Streams/ReadableStream-pipeTo-cannot-pipe-locked-stream.html
index 6621ef1724f..cef27d562b0 100644
--- a/Tests/LibWeb/Text/input/Streams/ReadableStream-pipeTo-cannot-pipe-locked-stream.html
+++ b/Tests/LibWeb/Text/input/Streams/ReadableStream-pipeTo-cannot-pipe-locked-stream.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest(done => {
diff --git a/Tests/LibWeb/Text/input/Streams/ReadableStream-pipeTo-cannot-pipe-to-locked-stream.html b/Tests/LibWeb/Text/input/Streams/ReadableStream-pipeTo-cannot-pipe-to-locked-stream.html
index 5b5a9374ed4..d075c791b39 100644
--- a/Tests/LibWeb/Text/input/Streams/ReadableStream-pipeTo-cannot-pipe-to-locked-stream.html
+++ b/Tests/LibWeb/Text/input/Streams/ReadableStream-pipeTo-cannot-pipe-to-locked-stream.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest(done => {
diff --git a/Tests/LibWeb/Text/input/Streams/ReadableStream-pipeTo.html b/Tests/LibWeb/Text/input/Streams/ReadableStream-pipeTo.html
index e73143a86b3..36d797fb513 100644
--- a/Tests/LibWeb/Text/input/Streams/ReadableStream-pipeTo.html
+++ b/Tests/LibWeb/Text/input/Streams/ReadableStream-pipeTo.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     const CHUNK1 =  "abcdefghijklmnopqrstuvwxyz";
diff --git a/Tests/LibWeb/Text/input/Streams/ReadableStreamBYOBReader-read-min.html b/Tests/LibWeb/Text/input/Streams/ReadableStreamBYOBReader-read-min.html
index e446f8b3ec8..f9b1bcad229 100644
--- a/Tests/LibWeb/Text/input/Streams/ReadableStreamBYOBReader-read-min.html
+++ b/Tests/LibWeb/Text/input/Streams/ReadableStreamBYOBReader-read-min.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     const CHUNK1 = "This -⌄";
diff --git a/Tests/LibWeb/Text/input/Streams/ReadableStreamBYOBReader-read.html b/Tests/LibWeb/Text/input/Streams/ReadableStreamBYOBReader-read.html
index 773422df51e..9928053e31b 100644
--- a/Tests/LibWeb/Text/input/Streams/ReadableStreamBYOBReader-read.html
+++ b/Tests/LibWeb/Text/input/Streams/ReadableStreamBYOBReader-read.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
  async function testByobRead(type) {
diff --git a/Tests/LibWeb/Text/input/Streams/ReadableStreamBYOBReader-respondWithNewView.html b/Tests/LibWeb/Text/input/Streams/ReadableStreamBYOBReader-respondWithNewView.html
index 0926b8efe36..4a6a5e7ccb1 100644
--- a/Tests/LibWeb/Text/input/Streams/ReadableStreamBYOBReader-respondWithNewView.html
+++ b/Tests/LibWeb/Text/input/Streams/ReadableStreamBYOBReader-respondWithNewView.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     const CHUNK1 = "abcdefghijklmnopqrstuvwxyz";
diff --git a/Tests/LibWeb/Text/input/Streams/TransformStream-cancelled-by-readable-side.html b/Tests/LibWeb/Text/input/Streams/TransformStream-cancelled-by-readable-side.html
index c6ad7cd2927..16ba1957a66 100644
--- a/Tests/LibWeb/Text/input/Streams/TransformStream-cancelled-by-readable-side.html
+++ b/Tests/LibWeb/Text/input/Streams/TransformStream-cancelled-by-readable-side.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     function testTransformStreamReadableStreamCancellation() {
diff --git a/Tests/LibWeb/Text/input/Streams/TransformStream-cancelled-by-writable-side.html b/Tests/LibWeb/Text/input/Streams/TransformStream-cancelled-by-writable-side.html
index 4207e8e5843..38d4dc33935 100644
--- a/Tests/LibWeb/Text/input/Streams/TransformStream-cancelled-by-writable-side.html
+++ b/Tests/LibWeb/Text/input/Streams/TransformStream-cancelled-by-writable-side.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     function testTransformStreamReadableStreamCancellation() {
diff --git a/Tests/LibWeb/Text/input/Streams/TransformStream-flush-callback.html b/Tests/LibWeb/Text/input/Streams/TransformStream-flush-callback.html
index fb3310bcdd2..f9300f91469 100644
--- a/Tests/LibWeb/Text/input/Streams/TransformStream-flush-callback.html
+++ b/Tests/LibWeb/Text/input/Streams/TransformStream-flush-callback.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
   test(() => {
diff --git a/Tests/LibWeb/Text/input/Streams/TransformStream-identity-transform.html b/Tests/LibWeb/Text/input/Streams/TransformStream-identity-transform.html
index ed777b92002..0f357c51bb5 100644
--- a/Tests/LibWeb/Text/input/Streams/TransformStream-identity-transform.html
+++ b/Tests/LibWeb/Text/input/Streams/TransformStream-identity-transform.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/Streams/TransformStream-readable-cancel.html b/Tests/LibWeb/Text/input/Streams/TransformStream-readable-cancel.html
index e6c11690caa..ff0913c660e 100644
--- a/Tests/LibWeb/Text/input/Streams/TransformStream-readable-cancel.html
+++ b/Tests/LibWeb/Text/input/Streams/TransformStream-readable-cancel.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/Streams/TransformStream-readableType-writableType-has-value.html b/Tests/LibWeb/Text/input/Streams/TransformStream-readableType-writableType-has-value.html
index d2510055e19..dd96a910805 100644
--- a/Tests/LibWeb/Text/input/Streams/TransformStream-readableType-writableType-has-value.html
+++ b/Tests/LibWeb/Text/input/Streams/TransformStream-readableType-writableType-has-value.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/Streams/TransformStream-start-callback.html b/Tests/LibWeb/Text/input/Streams/TransformStream-start-callback.html
index 2c94128d2fa..d4c2488b215 100644
--- a/Tests/LibWeb/Text/input/Streams/TransformStream-start-callback.html
+++ b/Tests/LibWeb/Text/input/Streams/TransformStream-start-callback.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/Streams/TransformStream-transform-callback.html b/Tests/LibWeb/Text/input/Streams/TransformStream-transform-callback.html
index f324ee4fa2b..9ac67572543 100644
--- a/Tests/LibWeb/Text/input/Streams/TransformStream-transform-callback.html
+++ b/Tests/LibWeb/Text/input/Streams/TransformStream-transform-callback.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/Streams/WritableStream-write.html b/Tests/LibWeb/Text/input/Streams/WritableStream-write.html
index 9ac9202305a..0799f625c39 100644
--- a/Tests/LibWeb/Text/input/Streams/WritableStream-write.html
+++ b/Tests/LibWeb/Text/input/Streams/WritableStream-write.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest(done => {
diff --git a/Tests/LibWeb/Text/input/Streams/init-from-cloned-fetch-response.html b/Tests/LibWeb/Text/input/Streams/init-from-cloned-fetch-response.html
index f61ad5fe5c5..be9a278921d 100644
--- a/Tests/LibWeb/Text/input/Streams/init-from-cloned-fetch-response.html
+++ b/Tests/LibWeb/Text/input/Streams/init-from-cloned-fetch-response.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest(async done => {
diff --git a/Tests/LibWeb/Text/input/Streams/init-from-fetch.html b/Tests/LibWeb/Text/input/Streams/init-from-fetch.html
index 851d5400708..b061cf56b11 100644
--- a/Tests/LibWeb/Text/input/Streams/init-from-fetch.html
+++ b/Tests/LibWeb/Text/input/Streams/init-from-fetch.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest(async done => {
diff --git a/Tests/LibWeb/Text/input/UIEvents/KeyEvent-cancelled.html b/Tests/LibWeb/Text/input/UIEvents/KeyEvent-cancelled.html
index 4d6ca512a60..37e015d0f29 100644
--- a/Tests/LibWeb/Text/input/UIEvents/KeyEvent-cancelled.html
+++ b/Tests/LibWeb/Text/input/UIEvents/KeyEvent-cancelled.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <input id="input" />
 <script src="../include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/UIEvents/KeyEvent-functional-keys.html b/Tests/LibWeb/Text/input/UIEvents/KeyEvent-functional-keys.html
index a11c6db13a3..022a74f55dd 100644
--- a/Tests/LibWeb/Text/input/UIEvents/KeyEvent-functional-keys.html
+++ b/Tests/LibWeb/Text/input/UIEvents/KeyEvent-functional-keys.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <input id="input" />
 <script src="../include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/UIEvents/KeyEvent-keypress.html b/Tests/LibWeb/Text/input/UIEvents/KeyEvent-keypress.html
index 4653c2259e7..50d8c52decb 100644
--- a/Tests/LibWeb/Text/input/UIEvents/KeyEvent-keypress.html
+++ b/Tests/LibWeb/Text/input/UIEvents/KeyEvent-keypress.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <input id="input" />
 <script src="../include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/UIEvents/KeyEvent-non-ascii.html b/Tests/LibWeb/Text/input/UIEvents/KeyEvent-non-ascii.html
index 69bbf48e136..7bed9d87f77 100644
--- a/Tests/LibWeb/Text/input/UIEvents/KeyEvent-non-ascii.html
+++ b/Tests/LibWeb/Text/input/UIEvents/KeyEvent-non-ascii.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <input id="input" />
 <script src="../include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/UIEvents/KeyEvent-numpad-keys.html b/Tests/LibWeb/Text/input/UIEvents/KeyEvent-numpad-keys.html
index 97041bc11c1..0ed139b1f45 100644
--- a/Tests/LibWeb/Text/input/UIEvents/KeyEvent-numpad-keys.html
+++ b/Tests/LibWeb/Text/input/UIEvents/KeyEvent-numpad-keys.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <input id="input" />
 <script src="../include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/UIEvents/KeyEvent-tab.html b/Tests/LibWeb/Text/input/UIEvents/KeyEvent-tab.html
index ee7b0478fc7..fc6f747042d 100644
--- a/Tests/LibWeb/Text/input/UIEvents/KeyEvent-tab.html
+++ b/Tests/LibWeb/Text/input/UIEvents/KeyEvent-tab.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <input id="input1" />
 <input id="input2" />
 <script src="../include.js"></script>
diff --git a/Tests/LibWeb/Text/input/UIEvents/MouseEvent-bubbling.html b/Tests/LibWeb/Text/input/UIEvents/MouseEvent-bubbling.html
index c2e56fe29f3..96cfb37b03a 100644
--- a/Tests/LibWeb/Text/input/UIEvents/MouseEvent-bubbling.html
+++ b/Tests/LibWeb/Text/input/UIEvents/MouseEvent-bubbling.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <style>
     * { border: 1px solid black; }
diff --git a/Tests/LibWeb/Text/input/UIEvents/PointerEvent-construction.html b/Tests/LibWeb/Text/input/UIEvents/PointerEvent-construction.html
index ff89544f871..54859fe356b 100644
--- a/Tests/LibWeb/Text/input/UIEvents/PointerEvent-construction.html
+++ b/Tests/LibWeb/Text/input/UIEvents/PointerEvent-construction.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     function dumpPointerEvent(event) {
diff --git a/Tests/LibWeb/Text/input/UIEvents/WheelEvent-bubbling.html b/Tests/LibWeb/Text/input/UIEvents/WheelEvent-bubbling.html
index 3299feb2400..34dd361a250 100644
--- a/Tests/LibWeb/Text/input/UIEvents/WheelEvent-bubbling.html
+++ b/Tests/LibWeb/Text/input/UIEvents/WheelEvent-bubbling.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <style>
     * { border: 1px solid black; }
diff --git a/Tests/LibWeb/Text/input/UIEvents/WheelEvent-construction.html b/Tests/LibWeb/Text/input/UIEvents/WheelEvent-construction.html
index 0bf06d26380..fe64936460b 100644
--- a/Tests/LibWeb/Text/input/UIEvents/WheelEvent-construction.html
+++ b/Tests/LibWeb/Text/input/UIEvents/WheelEvent-construction.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     function dumpWheelEvent(wheelEvent) {
diff --git a/Tests/LibWeb/Text/input/UIEvents/custom-keyboard-event.html b/Tests/LibWeb/Text/input/UIEvents/custom-keyboard-event.html
index badcd44219c..57c034c7dbd 100644
--- a/Tests/LibWeb/Text/input/UIEvents/custom-keyboard-event.html
+++ b/Tests/LibWeb/Text/input/UIEvents/custom-keyboard-event.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/UIEvents/custom-mouse-event.html b/Tests/LibWeb/Text/input/UIEvents/custom-mouse-event.html
index 52962c867d9..b058a61f054 100644
--- a/Tests/LibWeb/Text/input/UIEvents/custom-mouse-event.html
+++ b/Tests/LibWeb/Text/input/UIEvents/custom-mouse-event.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/URL/URL-operations-properties.html b/Tests/LibWeb/Text/input/URL/URL-operations-properties.html
index 7705ae8d207..314e83a1ac9 100644
--- a/Tests/LibWeb/Text/input/URL/URL-operations-properties.html
+++ b/Tests/LibWeb/Text/input/URL/URL-operations-properties.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/URL/invalid-urls.html b/Tests/LibWeb/Text/input/URL/invalid-urls.html
index bb0e774765f..08d8dab85d0 100644
--- a/Tests/LibWeb/Text/input/URL/invalid-urls.html
+++ b/Tests/LibWeb/Text/input/URL/invalid-urls.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/URL/opaque_paths_roundtrip.html b/Tests/LibWeb/Text/input/URL/opaque_paths_roundtrip.html
index c8c4dce7423..94c5ee8b34a 100644
--- a/Tests/LibWeb/Text/input/URL/opaque_paths_roundtrip.html
+++ b/Tests/LibWeb/Text/input/URL/opaque_paths_roundtrip.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/URL/search-params-delete.html b/Tests/LibWeb/Text/input/URL/search-params-delete.html
index e2ba9c17fb6..7b153de39f9 100644
--- a/Tests/LibWeb/Text/input/URL/search-params-delete.html
+++ b/Tests/LibWeb/Text/input/URL/search-params-delete.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/URL/search-params-has.html b/Tests/LibWeb/Text/input/URL/search-params-has.html
index d393eff766e..c6a51cfdba2 100644
--- a/Tests/LibWeb/Text/input/URL/search-params-has.html
+++ b/Tests/LibWeb/Text/input/URL/search-params-has.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/URL/search-params-strip-trailing-spaces-from-opaque-url.html b/Tests/LibWeb/Text/input/URL/search-params-strip-trailing-spaces-from-opaque-url.html
index 02f7a470a89..27e0ac8a8dc 100644
--- a/Tests/LibWeb/Text/input/URL/search-params-strip-trailing-spaces-from-opaque-url.html
+++ b/Tests/LibWeb/Text/input/URL/search-params-strip-trailing-spaces-from-opaque-url.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/URL/search-params-with-invalid-utf8.html b/Tests/LibWeb/Text/input/URL/search-params-with-invalid-utf8.html
index 4438a6c850c..d29387c65a1 100644
--- a/Tests/LibWeb/Text/input/URL/search-params-with-invalid-utf8.html
+++ b/Tests/LibWeb/Text/input/URL/search-params-with-invalid-utf8.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/URL/search-params-with-no-query.html b/Tests/LibWeb/Text/input/URL/search-params-with-no-query.html
index fba4c990143..2403ef6609a 100644
--- a/Tests/LibWeb/Text/input/URL/search-params-with-no-query.html
+++ b/Tests/LibWeb/Text/input/URL/search-params-with-no-query.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/URL/search-params-with-plus-in-value.html b/Tests/LibWeb/Text/input/URL/search-params-with-plus-in-value.html
index 3f5fa015847..272e87de6be 100644
--- a/Tests/LibWeb/Text/input/URL/search-params-with-plus-in-value.html
+++ b/Tests/LibWeb/Text/input/URL/search-params-with-plus-in-value.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/URL/set-href-with-valid-hostname-but-invalid-port.html b/Tests/LibWeb/Text/input/URL/set-href-with-valid-hostname-but-invalid-port.html
index e50b4f7d7c3..bb0e21b6df2 100644
--- a/Tests/LibWeb/Text/input/URL/set-href-with-valid-hostname-but-invalid-port.html
+++ b/Tests/LibWeb/Text/input/URL/set-href-with-valid-hostname-but-invalid-port.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <a id="id" href="http://example.net/path">
 <script src="../include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/URL/url-origin-for-blob-url-with-inner-ftp-scheme.html b/Tests/LibWeb/Text/input/URL/url-origin-for-blob-url-with-inner-ftp-scheme.html
index 5eef2d24007..3f62292448c 100644
--- a/Tests/LibWeb/Text/input/URL/url-origin-for-blob-url-with-inner-ftp-scheme.html
+++ b/Tests/LibWeb/Text/input/URL/url-origin-for-blob-url-with-inner-ftp-scheme.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <a id="a" href='blob:ftp://host/path'>
 <script src="../include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/URL/url-origin-for-port-number-of-zero.html b/Tests/LibWeb/Text/input/URL/url-origin-for-port-number-of-zero.html
index 03857d3efc4..2e83013128d 100644
--- a/Tests/LibWeb/Text/input/URL/url-origin-for-port-number-of-zero.html
+++ b/Tests/LibWeb/Text/input/URL/url-origin-for-port-number-of-zero.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <a id="a" href='http://f:0/c'>
 <script src="../include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/URL/url-search-params-iterator-iterator.html b/Tests/LibWeb/Text/input/URL/url-search-params-iterator-iterator.html
index 5ee98c581f8..83cf350bdff 100644
--- a/Tests/LibWeb/Text/input/URL/url-search-params-iterator-iterator.html
+++ b/Tests/LibWeb/Text/input/URL/url-search-params-iterator-iterator.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/URL/url-search-params-sort-order-stable.html b/Tests/LibWeb/Text/input/URL/url-search-params-sort-order-stable.html
index 8598b8dfb7e..b3e16dd7ced 100644
--- a/Tests/LibWeb/Text/input/URL/url-search-params-sort-order-stable.html
+++ b/Tests/LibWeb/Text/input/URL/url-search-params-sort-order-stable.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/URL/url-search-params-sort-utf16-code-units.html b/Tests/LibWeb/Text/input/URL/url-search-params-sort-utf16-code-units.html
index 1101024bcfa..422fe9cf624 100644
--- a/Tests/LibWeb/Text/input/URL/url-search-params-sort-utf16-code-units.html
+++ b/Tests/LibWeb/Text/input/URL/url-search-params-sort-utf16-code-units.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     function escapeUnicode(str) {
diff --git a/Tests/LibWeb/Text/input/URL/url.html b/Tests/LibWeb/Text/input/URL/url.html
index 77c79fafff6..b84b8842282 100644
--- a/Tests/LibWeb/Text/input/URL/url.html
+++ b/Tests/LibWeb/Text/input/URL/url.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/Wasm/WebAssembly-grow.html b/Tests/LibWeb/Text/input/Wasm/WebAssembly-grow.html
index 53f5d612efb..209430cde06 100644
--- a/Tests/LibWeb/Text/input/Wasm/WebAssembly-grow.html
+++ b/Tests/LibWeb/Text/input/Wasm/WebAssembly-grow.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/Wasm/WebAssembly-instantiate.html b/Tests/LibWeb/Text/input/Wasm/WebAssembly-instantiate.html
index 70a26d769d8..7678ff3dc57 100644
--- a/Tests/LibWeb/Text/input/Wasm/WebAssembly-instantiate.html
+++ b/Tests/LibWeb/Text/input/Wasm/WebAssembly-instantiate.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest(async (done) => {
diff --git a/Tests/LibWeb/Text/input/WebAnimations/misc/animating-unresolved-properties-crash.html b/Tests/LibWeb/Text/input/WebAnimations/misc/animating-unresolved-properties-crash.html
index 71d46f6ea62..fe267fae2e4 100644
--- a/Tests/LibWeb/Text/input/WebAnimations/misc/animating-unresolved-properties-crash.html
+++ b/Tests/LibWeb/Text/input/WebAnimations/misc/animating-unresolved-properties-crash.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <!-- https://github.com/SerenityOS/serenity/issues/23609 -->
 <style>
     :root {
diff --git a/Tests/LibWeb/Text/input/WebAnimations/misc/animation-single-iteration-no-repeat.html b/Tests/LibWeb/Text/input/WebAnimations/misc/animation-single-iteration-no-repeat.html
index 95d28a47091..e043c438168 100644
--- a/Tests/LibWeb/Text/input/WebAnimations/misc/animation-single-iteration-no-repeat.html
+++ b/Tests/LibWeb/Text/input/WebAnimations/misc/animation-single-iteration-no-repeat.html
@@ -1,5 +1,5 @@
-<!-- https://github.com/SerenityOS/serenity/issues/23716 -->
 <!DOCTYPE html>
+<!-- https://github.com/SerenityOS/serenity/issues/23716 -->
 <style>
     #foo {
         animation: anim 1s;
diff --git a/Tests/LibWeb/Text/input/WebAnimations/transition-unknown-property.html b/Tests/LibWeb/Text/input/WebAnimations/transition-unknown-property.html
index 189029b9751..d99609dc392 100644
--- a/Tests/LibWeb/Text/input/WebAnimations/transition-unknown-property.html
+++ b/Tests/LibWeb/Text/input/WebAnimations/transition-unknown-property.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <style>
 #foo {
     transition-property: filter;
diff --git a/Tests/LibWeb/Text/input/WebAudio/AudioBuffer-copyFromChannel.html b/Tests/LibWeb/Text/input/WebAudio/AudioBuffer-copyFromChannel.html
index eef5da38d57..6afaa8a9b8e 100644
--- a/Tests/LibWeb/Text/input/WebAudio/AudioBuffer-copyFromChannel.html
+++ b/Tests/LibWeb/Text/input/WebAudio/AudioBuffer-copyFromChannel.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/WebAudio/AudioBuffer-copyToChannel.html b/Tests/LibWeb/Text/input/WebAudio/AudioBuffer-copyToChannel.html
index 2ba85faf1da..7fb5deb3df5 100644
--- a/Tests/LibWeb/Text/input/WebAudio/AudioBuffer-copyToChannel.html
+++ b/Tests/LibWeb/Text/input/WebAudio/AudioBuffer-copyToChannel.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/WebAudio/AudioBuffer.html b/Tests/LibWeb/Text/input/WebAudio/AudioBuffer.html
index cf243fdfc98..74f8d03dfe5 100644
--- a/Tests/LibWeb/Text/input/WebAudio/AudioBuffer.html
+++ b/Tests/LibWeb/Text/input/WebAudio/AudioBuffer.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/WebAudio/AudioListener.html b/Tests/LibWeb/Text/input/WebAudio/AudioListener.html
index eb126cf938a..a5e4449b947 100644
--- a/Tests/LibWeb/Text/input/WebAudio/AudioListener.html
+++ b/Tests/LibWeb/Text/input/WebAudio/AudioListener.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     function dumpAudioParam(param) {
diff --git a/Tests/LibWeb/Text/input/WebAudio/DynamicsCompressorNode.html b/Tests/LibWeb/Text/input/WebAudio/DynamicsCompressorNode.html
index e3c5a4bb37f..31acf5f71ef 100644
--- a/Tests/LibWeb/Text/input/WebAudio/DynamicsCompressorNode.html
+++ b/Tests/LibWeb/Text/input/WebAudio/DynamicsCompressorNode.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     function dumpAudioParam(param) {
diff --git a/Tests/LibWeb/Text/input/WebAudio/GainNode.html b/Tests/LibWeb/Text/input/WebAudio/GainNode.html
index 5570980b7da..56a4231fbbd 100644
--- a/Tests/LibWeb/Text/input/WebAudio/GainNode.html
+++ b/Tests/LibWeb/Text/input/WebAudio/GainNode.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     function dumpAudioParam(param) {
diff --git a/Tests/LibWeb/Text/input/WebAudio/OscillatorNode.html b/Tests/LibWeb/Text/input/WebAudio/OscillatorNode.html
index 408c7b92155..2ed2528df7c 100644
--- a/Tests/LibWeb/Text/input/WebAudio/OscillatorNode.html
+++ b/Tests/LibWeb/Text/input/WebAudio/OscillatorNode.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     function dumpAudioParam(param) {
diff --git a/Tests/LibWeb/Text/input/WebAudio/PannerNode.html b/Tests/LibWeb/Text/input/WebAudio/PannerNode.html
index 81a540b5669..6bbb921d7a3 100644
--- a/Tests/LibWeb/Text/input/WebAudio/PannerNode.html
+++ b/Tests/LibWeb/Text/input/WebAudio/PannerNode.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     function dumpAudioParam(param) {
diff --git a/Tests/LibWeb/Text/input/WebAudio/compressor-node-channel-cound-mode.html b/Tests/LibWeb/Text/input/WebAudio/compressor-node-channel-cound-mode.html
index 096b3a17f10..9c11e3b1704 100644
--- a/Tests/LibWeb/Text/input/WebAudio/compressor-node-channel-cound-mode.html
+++ b/Tests/LibWeb/Text/input/WebAudio/compressor-node-channel-cound-mode.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
 test(() => {
diff --git a/Tests/LibWeb/Text/input/WebSocket/WebSocket-gc.html b/Tests/LibWeb/Text/input/WebSocket/WebSocket-gc.html
index 83cc664e5b2..99b74db3a41 100644
--- a/Tests/LibWeb/Text/input/WebSocket/WebSocket-gc.html
+++ b/Tests/LibWeb/Text/input/WebSocket/WebSocket-gc.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest((done) => {
diff --git a/Tests/LibWeb/Text/input/WebSocket/echo.html b/Tests/LibWeb/Text/input/WebSocket/echo.html
index 6190005ec8f..41d70b66240 100644
--- a/Tests/LibWeb/Text/input/WebSocket/echo.html
+++ b/Tests/LibWeb/Text/input/WebSocket/echo.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest((done) => {
diff --git a/Tests/LibWeb/Text/input/Worker/Worker-blob.html b/Tests/LibWeb/Text/input/Worker/Worker-blob.html
index 2533294c653..410c9747c39 100644
--- a/Tests/LibWeb/Text/input/Worker/Worker-blob.html
+++ b/Tests/LibWeb/Text/input/Worker/Worker-blob.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest((done) => {
diff --git a/Tests/LibWeb/Text/input/Worker/Worker-crypto.html b/Tests/LibWeb/Text/input/Worker/Worker-crypto.html
index c8b59e57508..0c368ad03a8 100644
--- a/Tests/LibWeb/Text/input/Worker/Worker-crypto.html
+++ b/Tests/LibWeb/Text/input/Worker/Worker-crypto.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest(done => {
diff --git a/Tests/LibWeb/Text/input/Worker/Worker-echo.html b/Tests/LibWeb/Text/input/Worker/Worker-echo.html
index b8695264620..f2f263914c9 100644
--- a/Tests/LibWeb/Text/input/Worker/Worker-echo.html
+++ b/Tests/LibWeb/Text/input/Worker/Worker-echo.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest((done) => {
diff --git a/Tests/LibWeb/Text/input/Worker/Worker-importScripts.html b/Tests/LibWeb/Text/input/Worker/Worker-importScripts.html
index 80403b87b06..de0c4992fbf 100644
--- a/Tests/LibWeb/Text/input/Worker/Worker-importScripts.html
+++ b/Tests/LibWeb/Text/input/Worker/Worker-importScripts.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest((done) => {
diff --git a/Tests/LibWeb/Text/input/Worker/Worker-location.html b/Tests/LibWeb/Text/input/Worker/Worker-location.html
index 197493de833..ed76be2446f 100644
--- a/Tests/LibWeb/Text/input/Worker/Worker-location.html
+++ b/Tests/LibWeb/Text/input/Worker/Worker-location.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest(done => {
diff --git a/Tests/LibWeb/Text/input/Worker/Worker-module.html b/Tests/LibWeb/Text/input/Worker/Worker-module.html
index 604cd0987f8..05bced70bd8 100644
--- a/Tests/LibWeb/Text/input/Worker/Worker-module.html
+++ b/Tests/LibWeb/Text/input/Worker/Worker-module.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest((done) => {
diff --git a/Tests/LibWeb/Text/input/Worker/Worker-performance.html b/Tests/LibWeb/Text/input/Worker/Worker-performance.html
index fe82ace0cc2..d20deee97f2 100644
--- a/Tests/LibWeb/Text/input/Worker/Worker-performance.html
+++ b/Tests/LibWeb/Text/input/Worker/Worker-performance.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest(done => {
diff --git a/Tests/LibWeb/Text/input/Worker/Worker-postMessage-transfer.html b/Tests/LibWeb/Text/input/Worker/Worker-postMessage-transfer.html
index a514e6afaca..21fec01d009 100644
--- a/Tests/LibWeb/Text/input/Worker/Worker-postMessage-transfer.html
+++ b/Tests/LibWeb/Text/input/Worker/Worker-postMessage-transfer.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest((done) => {
diff --git a/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-forbidden-method.html b/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-forbidden-method.html
index 3c2c0e93478..21352db2d6e 100644
--- a/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-forbidden-method.html
+++ b/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-forbidden-method.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-invalid-or-illegal-method.html b/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-invalid-or-illegal-method.html
index 78a67b674de..d49c6635b89 100644
--- a/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-invalid-or-illegal-method.html
+++ b/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-invalid-or-illegal-method.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-request-is-blob.html b/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-request-is-blob.html
index febbfeac575..067dd551dfe 100644
--- a/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-request-is-blob.html
+++ b/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-request-is-blob.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest(done => {
diff --git a/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-response-empty.html b/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-response-empty.html
index c93249dfb4c..3b99edc34d7 100644
--- a/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-response-empty.html
+++ b/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-response-empty.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest((done) => {
diff --git a/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-response-gives-Document.html b/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-response-gives-Document.html
index 9fa0e69d793..f8f31a0d248 100644
--- a/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-response-gives-Document.html
+++ b/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-response-gives-Document.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest((done) => {
diff --git a/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-response-header-decoding.html b/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-response-header-decoding.html
index f43133a8b7d..f6caf4d8cc0 100644
--- a/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-response-header-decoding.html
+++ b/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-response-header-decoding.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest(async (done) => {
diff --git a/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-response-is-arraybuffer.html b/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-response-is-arraybuffer.html
index f8c92551919..d2bee9f12ac 100644
--- a/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-response-is-arraybuffer.html
+++ b/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-response-is-arraybuffer.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest((done) => {
diff --git a/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-response-is-blob.html b/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-response-is-blob.html
index 16f8993b38c..f0bfebf8586 100644
--- a/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-response-is-blob.html
+++ b/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-response-is-blob.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest((done) => {
diff --git a/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-response-is-json-number.html b/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-response-is-json-number.html
index 9324e6ec5b6..810500f9cb8 100644
--- a/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-response-is-json-number.html
+++ b/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-response-is-json-number.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest((done) => {
diff --git a/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-responseURL.html b/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-responseURL.html
index 19a2c72b4e1..850588118e5 100644
--- a/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-responseURL.html
+++ b/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-responseURL.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest((done) => {
diff --git a/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-responseXML-empty.html b/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-responseXML-empty.html
index eba94864af6..bfd0a360bdb 100644
--- a/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-responseXML-empty.html
+++ b/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-responseXML-empty.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest((done) => {
diff --git a/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-responseXML-gives-XMLDocument.html b/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-responseXML-gives-XMLDocument.html
index 54c785cbf57..2786f63fd48 100644
--- a/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-responseXML-gives-XMLDocument.html
+++ b/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-responseXML-gives-XMLDocument.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest((done) => {
diff --git a/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-send-flag-already-set.html b/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-send-flag-already-set.html
index 9abd30f51d6..603fca4ae00 100644
--- a/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-send-flag-already-set.html
+++ b/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-send-flag-already-set.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-state-not-opened.html b/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-state-not-opened.html
index 3008c44dc9d..c5f8eb363df 100644
--- a/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-state-not-opened.html
+++ b/Tests/LibWeb/Text/input/XHR/XMLHttpRequest-state-not-opened.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/XML/error-page.html b/Tests/LibWeb/Text/input/XML/error-page.html
index 634cd603477..3d44f1aeddc 100644
--- a/Tests/LibWeb/Text/input/XML/error-page.html
+++ b/Tests/LibWeb/Text/input/XML/error-page.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <iframe id="i1"></iframe>
 <script>
diff --git a/Tests/LibWeb/Text/input/XML/parser-namespace.html b/Tests/LibWeb/Text/input/XML/parser-namespace.html
index 67074c2b285..b2a84d43183 100644
--- a/Tests/LibWeb/Text/input/XML/parser-namespace.html
+++ b/Tests/LibWeb/Text/input/XML/parser-namespace.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest((done) => {
diff --git a/Tests/LibWeb/Text/input/abortsignal-abort.html b/Tests/LibWeb/Text/input/abortsignal-abort.html
index 4f7b088e4d8..93668f66c95 100644
--- a/Tests/LibWeb/Text/input/abortsignal-abort.html
+++ b/Tests/LibWeb/Text/input/abortsignal-abort.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <script>
     asyncTest(async done => {
diff --git a/Tests/LibWeb/Text/input/abortsignal-any.html b/Tests/LibWeb/Text/input/abortsignal-any.html
index b76dc8ebffb..14ce5527960 100644
--- a/Tests/LibWeb/Text/input/abortsignal-any.html
+++ b/Tests/LibWeb/Text/input/abortsignal-any.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/abortsignal-timeout.html b/Tests/LibWeb/Text/input/abortsignal-timeout.html
index 82a825b36d8..8904b217319 100644
--- a/Tests/LibWeb/Text/input/abortsignal-timeout.html
+++ b/Tests/LibWeb/Text/input/abortsignal-timeout.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <script>
     asyncTest(done => {
diff --git a/Tests/LibWeb/Text/input/alert.html b/Tests/LibWeb/Text/input/alert.html
index 94d51ad8ec6..bf758b5a17e 100644
--- a/Tests/LibWeb/Text/input/alert.html
+++ b/Tests/LibWeb/Text/input/alert.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/all-window-properties.html b/Tests/LibWeb/Text/input/all-window-properties.html
index 412bcda1b08..1ca0e3b0681 100644
--- a/Tests/LibWeb/Text/input/all-window-properties.html
+++ b/Tests/LibWeb/Text/input/all-window-properties.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/anchor-element-with-javascript-url-href.html b/Tests/LibWeb/Text/input/anchor-element-with-javascript-url-href.html
index 389a519ee85..b3dfd6bee74 100644
--- a/Tests/LibWeb/Text/input/anchor-element-with-javascript-url-href.html
+++ b/Tests/LibWeb/Text/input/anchor-element-with-javascript-url-href.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <script>
 function javascript_navigation_callback() {
diff --git a/Tests/LibWeb/Text/input/append-child-must-update-layout-tree.html b/Tests/LibWeb/Text/input/append-child-must-update-layout-tree.html
index 8bd7944db0a..169fcb7dc2e 100644
--- a/Tests/LibWeb/Text/input/append-child-must-update-layout-tree.html
+++ b/Tests/LibWeb/Text/input/append-child-must-update-layout-tree.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/background-position-xy.html b/Tests/LibWeb/Text/input/background-position-xy.html
index 14ba2b52396..fea45634441 100644
--- a/Tests/LibWeb/Text/input/background-position-xy.html
+++ b/Tests/LibWeb/Text/input/background-position-xy.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/basic.html b/Tests/LibWeb/Text/input/basic.html
index 7a9a31f71f4..28b2994f408 100644
--- a/Tests/LibWeb/Text/input/basic.html
+++ b/Tests/LibWeb/Text/input/basic.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/border-radius-div-containing-iframe-with-border-radius-svg.html b/Tests/LibWeb/Text/input/border-radius-div-containing-iframe-with-border-radius-svg.html
index 67cccf1d470..04996f1a1c4 100644
--- a/Tests/LibWeb/Text/input/border-radius-div-containing-iframe-with-border-radius-svg.html
+++ b/Tests/LibWeb/Text/input/border-radius-div-containing-iframe-with-border-radius-svg.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <style>
     div {
         border-radius: 1px;
diff --git a/Tests/LibWeb/Text/input/canvas/2d-canvas-create-imagedata.html b/Tests/LibWeb/Text/input/canvas/2d-canvas-create-imagedata.html
index 783456b22ff..bfed9916422 100644
--- a/Tests/LibWeb/Text/input/canvas/2d-canvas-create-imagedata.html
+++ b/Tests/LibWeb/Text/input/canvas/2d-canvas-create-imagedata.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/canvas/basic.html b/Tests/LibWeb/Text/input/canvas/basic.html
index 8eeb3fe0c14..74c69c4cd71 100644
--- a/Tests/LibWeb/Text/input/canvas/basic.html
+++ b/Tests/LibWeb/Text/input/canvas/basic.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/canvas/convert-dims.html b/Tests/LibWeb/Text/input/canvas/convert-dims.html
index b454df3edac..40419b962c5 100644
--- a/Tests/LibWeb/Text/input/canvas/convert-dims.html
+++ b/Tests/LibWeb/Text/input/canvas/convert-dims.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <canvas id="c" class="output" width="11" height="11"><p class="fallback">FAIL (fallback content)</p></canvas>
 <script src="../include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/canvas/export.html b/Tests/LibWeb/Text/input/canvas/export.html
index 982a0a45113..ee3ed73d63e 100644
--- a/Tests/LibWeb/Text/input/canvas/export.html
+++ b/Tests/LibWeb/Text/input/canvas/export.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/canvas/fillStyle-bogus-rgba-color.html b/Tests/LibWeb/Text/input/canvas/fillStyle-bogus-rgba-color.html
index 02a32f6f324..337d9634a07 100644
--- a/Tests/LibWeb/Text/input/canvas/fillStyle-bogus-rgba-color.html
+++ b/Tests/LibWeb/Text/input/canvas/fillStyle-bogus-rgba-color.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <canvas id="c" width=300 height=300></canvas>
 <script>
diff --git a/Tests/LibWeb/Text/input/canvas/fillStyle-serialization.html b/Tests/LibWeb/Text/input/canvas/fillStyle-serialization.html
index c823232e387..9c6583011f8 100644
--- a/Tests/LibWeb/Text/input/canvas/fillStyle-serialization.html
+++ b/Tests/LibWeb/Text/input/canvas/fillStyle-serialization.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <canvas id="c" width=300 height=300></canvas>
 <script>
diff --git a/Tests/LibWeb/Text/input/canvas/fillstyle.html b/Tests/LibWeb/Text/input/canvas/fillstyle.html
index 1b2830effdc..dc67e2ac224 100644
--- a/Tests/LibWeb/Text/input/canvas/fillstyle.html
+++ b/Tests/LibWeb/Text/input/canvas/fillstyle.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/canvas/invalid-font-property.html b/Tests/LibWeb/Text/input/canvas/invalid-font-property.html
index ee94df86c46..aca856cc888 100644
--- a/Tests/LibWeb/Text/input/canvas/invalid-font-property.html
+++ b/Tests/LibWeb/Text/input/canvas/invalid-font-property.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/canvas/pattern-from-image.html b/Tests/LibWeb/Text/input/canvas/pattern-from-image.html
index 7b680d57539..d39701bfe9b 100644
--- a/Tests/LibWeb/Text/input/canvas/pattern-from-image.html
+++ b/Tests/LibWeb/Text/input/canvas/pattern-from-image.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/canvas/pattern-from-video.html b/Tests/LibWeb/Text/input/canvas/pattern-from-video.html
index 68118f3144b..34a546dc039 100644
--- a/Tests/LibWeb/Text/input/canvas/pattern-from-video.html
+++ b/Tests/LibWeb/Text/input/canvas/pattern-from-video.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/canvas/transform.html b/Tests/LibWeb/Text/input/canvas/transform.html
index 5956895632a..59b3656e29a 100644
--- a/Tests/LibWeb/Text/input/canvas/transform.html
+++ b/Tests/LibWeb/Text/input/canvas/transform.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/clipboard.html b/Tests/LibWeb/Text/input/clipboard.html
index dfc6d391db5..a3460b74f28 100644
--- a/Tests/LibWeb/Text/input/clipboard.html
+++ b/Tests/LibWeb/Text/input/clipboard.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <button id="button"></button>
 <script src="include.js"></script>
 <script type="text/javascript">
diff --git a/Tests/LibWeb/Text/input/close-non-modal-dialog.html b/Tests/LibWeb/Text/input/close-non-modal-dialog.html
index 21ee6eb268a..df3df9a07dc 100644
--- a/Tests/LibWeb/Text/input/close-non-modal-dialog.html
+++ b/Tests/LibWeb/Text/input/close-non-modal-dialog.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="./include.js"></script>
 <dialog id="test-dialog" open></dialog>
 <script>
diff --git a/Tests/LibWeb/Text/input/collapse-selection-inside-shadow-root.html b/Tests/LibWeb/Text/input/collapse-selection-inside-shadow-root.html
index a7633c5ed1c..ba397bed5a6 100644
--- a/Tests/LibWeb/Text/input/collapse-selection-inside-shadow-root.html
+++ b/Tests/LibWeb/Text/input/collapse-selection-inside-shadow-root.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <button id="button1"></button>
 <div id="root"></div>
diff --git a/Tests/LibWeb/Text/input/console/console-prototype.html b/Tests/LibWeb/Text/input/console/console-prototype.html
index d1c1dc1bf5e..96458a8fa1b 100644
--- a/Tests/LibWeb/Text/input/console/console-prototype.html
+++ b/Tests/LibWeb/Text/input/console/console-prototype.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/console/console-to-string-tag.html b/Tests/LibWeb/Text/input/console/console-to-string-tag.html
index 06460612311..f9231d9b345 100644
--- a/Tests/LibWeb/Text/input/console/console-to-string-tag.html
+++ b/Tests/LibWeb/Text/input/console/console-to-string-tag.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/contenteditable-should-insert-into-nested-node.html b/Tests/LibWeb/Text/input/contenteditable-should-insert-into-nested-node.html
index 5aee244b769..5ccac04c0cb 100644
--- a/Tests/LibWeb/Text/input/contenteditable-should-insert-into-nested-node.html
+++ b/Tests/LibWeb/Text/input/contenteditable-should-insert-into-nested-node.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <div id="editable" contenteditable="true"><p id="text">hello</p></div>
 <script>
diff --git a/Tests/LibWeb/Text/input/cookie.html b/Tests/LibWeb/Text/input/cookie.html
index 2d4cc511778..98fa3726869 100644
--- a/Tests/LibWeb/Text/input/cookie.html
+++ b/Tests/LibWeb/Text/input/cookie.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <div id="test"></div>
 <script src="include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/createBitmap.html b/Tests/LibWeb/Text/input/createBitmap.html
index 2026687b00f..a8262e48df7 100644
--- a/Tests/LibWeb/Text/input/createBitmap.html
+++ b/Tests/LibWeb/Text/input/createBitmap.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <canvas id="test" width="2" height="2" hidden="hidden"></canvas>
 <script>
diff --git a/Tests/LibWeb/Text/input/css-shadow-host-selector-matching.html b/Tests/LibWeb/Text/input/css-shadow-host-selector-matching.html
index 18f3a99c0e4..98e872075d2 100644
--- a/Tests/LibWeb/Text/input/css-shadow-host-selector-matching.html
+++ b/Tests/LibWeb/Text/input/css-shadow-host-selector-matching.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/css/FontFaceSet-load.html b/Tests/LibWeb/Text/input/css/FontFaceSet-load.html
index 23553e71b05..2590aa43431 100644
--- a/Tests/LibWeb/Text/input/css/FontFaceSet-load.html
+++ b/Tests/LibWeb/Text/input/css/FontFaceSet-load.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script type="text/javascript">
     asyncTest(async done => {
diff --git a/Tests/LibWeb/Text/input/css/PropertyOwningCSSStyleDeclaration-serialized-custom-properties.html b/Tests/LibWeb/Text/input/css/PropertyOwningCSSStyleDeclaration-serialized-custom-properties.html
index c84538eca3a..521ddfb2ca5 100644
--- a/Tests/LibWeb/Text/input/css/PropertyOwningCSSStyleDeclaration-serialized-custom-properties.html
+++ b/Tests/LibWeb/Text/input/css/PropertyOwningCSSStyleDeclaration-serialized-custom-properties.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/css/animating-transform-with-calc-crash.html b/Tests/LibWeb/Text/input/css/animating-transform-with-calc-crash.html
index f3009811589..c66b64fd9a7 100644
--- a/Tests/LibWeb/Text/input/css/animating-transform-with-calc-crash.html
+++ b/Tests/LibWeb/Text/input/css/animating-transform-with-calc-crash.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <!-- https://github.com/SerenityOS/serenity/issues/23633 -->
 <style>
     div {
diff --git a/Tests/LibWeb/Text/input/css/animating-unresolved-properties-crash.html b/Tests/LibWeb/Text/input/css/animating-unresolved-properties-crash.html
index 055f97a78fb..3d6943fe727 100644
--- a/Tests/LibWeb/Text/input/css/animating-unresolved-properties-crash.html
+++ b/Tests/LibWeb/Text/input/css/animating-unresolved-properties-crash.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <!-- https://github.com/SerenityOS/serenity/issues/23609 -->
 <style>
     :root {
diff --git a/Tests/LibWeb/Text/input/css/attr-serialization.html b/Tests/LibWeb/Text/input/css/attr-serialization.html
index 51f312b2089..33343d70d56 100644
--- a/Tests/LibWeb/Text/input/css/attr-serialization.html
+++ b/Tests/LibWeb/Text/input/css/attr-serialization.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/css/box-shadow-resolves-length-functions.html b/Tests/LibWeb/Text/input/css/box-shadow-resolves-length-functions.html
index 81bc32cdc1d..1d90a20c7bb 100644
--- a/Tests/LibWeb/Text/input/css/box-shadow-resolves-length-functions.html
+++ b/Tests/LibWeb/Text/input/css/box-shadow-resolves-length-functions.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/css/calc-missing-context.html b/Tests/LibWeb/Text/input/css/calc-missing-context.html
index 19b28454c57..7119dae8a29 100644
--- a/Tests/LibWeb/Text/input/css/calc-missing-context.html
+++ b/Tests/LibWeb/Text/input/css/calc-missing-context.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/css/changing-animation-name-crash.html b/Tests/LibWeb/Text/input/css/changing-animation-name-crash.html
index 6b7a5b504d0..79b7b6862be 100644
--- a/Tests/LibWeb/Text/input/css/changing-animation-name-crash.html
+++ b/Tests/LibWeb/Text/input/css/changing-animation-name-crash.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <style>
     #foo {
         animation-name: rule1;
diff --git a/Tests/LibWeb/Text/input/css/cssFloat-property.html b/Tests/LibWeb/Text/input/css/cssFloat-property.html
index a3f197df2fe..f83957f2f04 100644
--- a/Tests/LibWeb/Text/input/css/cssFloat-property.html
+++ b/Tests/LibWeb/Text/input/css/cssFloat-property.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <style>
 span {
     float: right;
diff --git a/Tests/LibWeb/Text/input/css/custom-ident-parsing.html b/Tests/LibWeb/Text/input/css/custom-ident-parsing.html
index 99a247c9316..046fc52a81e 100644
--- a/Tests/LibWeb/Text/input/css/custom-ident-parsing.html
+++ b/Tests/LibWeb/Text/input/css/custom-ident-parsing.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div id="foo"></div>
 <script>
diff --git a/Tests/LibWeb/Text/input/css/custom-properties-from-all-layers.html b/Tests/LibWeb/Text/input/css/custom-properties-from-all-layers.html
index c8251a21e0c..a685ca3421d 100644
--- a/Tests/LibWeb/Text/input/css/custom-properties-from-all-layers.html
+++ b/Tests/LibWeb/Text/input/css/custom-properties-from-all-layers.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <style>
 :root { --top: 1px; }
 @layer foo { :root { --left: 2px; } }
diff --git a/Tests/LibWeb/Text/input/css/element-opacity-change-invalidation.html b/Tests/LibWeb/Text/input/css/element-opacity-change-invalidation.html
index 3591f9e349e..dec313b45a3 100644
--- a/Tests/LibWeb/Text/input/css/element-opacity-change-invalidation.html
+++ b/Tests/LibWeb/Text/input/css/element-opacity-change-invalidation.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/css/font-face-serialization.html b/Tests/LibWeb/Text/input/css/font-face-serialization.html
index 34849e46139..0e86f7999f7 100644
--- a/Tests/LibWeb/Text/input/css/font-face-serialization.html
+++ b/Tests/LibWeb/Text/input/css/font-face-serialization.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/css/font-family-with-dash-prefix.html b/Tests/LibWeb/Text/input/css/font-family-with-dash-prefix.html
index 84d10f3a1dc..8e3b3e44656 100644
--- a/Tests/LibWeb/Text/input/css/font-family-with-dash-prefix.html
+++ b/Tests/LibWeb/Text/input/css/font-family-with-dash-prefix.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/css/font-size-rem-units-on-root-element.html b/Tests/LibWeb/Text/input/css/font-size-rem-units-on-root-element.html
index 4a8d30c05b2..afd897f1741 100644
--- a/Tests/LibWeb/Text/input/css/font-size-rem-units-on-root-element.html
+++ b/Tests/LibWeb/Text/input/css/font-size-rem-units-on-root-element.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <style>
 :root { font-size: 1.1rem; }
 #whf { width: max-content; }
diff --git a/Tests/LibWeb/Text/input/css/getComputedStyle-display-short-serialization.html b/Tests/LibWeb/Text/input/css/getComputedStyle-display-short-serialization.html
index c535a8c4e8e..3d43d8fa5e3 100644
--- a/Tests/LibWeb/Text/input/css/getComputedStyle-display-short-serialization.html
+++ b/Tests/LibWeb/Text/input/css/getComputedStyle-display-short-serialization.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/css/getComputedStyle-print-all.html b/Tests/LibWeb/Text/input/css/getComputedStyle-print-all.html
index 5797f716deb..fd070dcde2e 100644
--- a/Tests/LibWeb/Text/input/css/getComputedStyle-print-all.html
+++ b/Tests/LibWeb/Text/input/css/getComputedStyle-print-all.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/css/getComputedStyle-transform.html b/Tests/LibWeb/Text/input/css/getComputedStyle-transform.html
index a64da1cffb5..3805723dc29 100644
--- a/Tests/LibWeb/Text/input/css/getComputedStyle-transform.html
+++ b/Tests/LibWeb/Text/input/css/getComputedStyle-transform.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/css/import-rule-shift-jis.html b/Tests/LibWeb/Text/input/css/import-rule-shift-jis.html
index 6a30019f081..05fca9af31d 100644
--- a/Tests/LibWeb/Text/input/css/import-rule-shift-jis.html
+++ b/Tests/LibWeb/Text/input/css/import-rule-shift-jis.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <style>
     @import "data:text/css;charset=shift_jis;base64,77u/I2RpdjIKewogICAgY29sb3I6IGdyZWVuOwp9Cgoulb2YYQp7CiAgICBjb2xvcjogcmVkOwp9Cg==";
 </style>
diff --git a/Tests/LibWeb/Text/input/css/keyframes-css-rules.html b/Tests/LibWeb/Text/input/css/keyframes-css-rules.html
index d920b1cd6da..82cb500d235 100644
--- a/Tests/LibWeb/Text/input/css/keyframes-css-rules.html
+++ b/Tests/LibWeb/Text/input/css/keyframes-css-rules.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <style>
 @keyframes foo {
     from { color: black; }
diff --git a/Tests/LibWeb/Text/input/css/legacy-color-value.html b/Tests/LibWeb/Text/input/css/legacy-color-value.html
index 9e14ff69ce0..b61ab7946b1 100644
--- a/Tests/LibWeb/Text/input/css/legacy-color-value.html
+++ b/Tests/LibWeb/Text/input/css/legacy-color-value.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/css/math-depth.html b/Tests/LibWeb/Text/input/css/math-depth.html
index 0e0ca670ce4..50df3454f41 100644
--- a/Tests/LibWeb/Text/input/css/math-depth.html
+++ b/Tests/LibWeb/Text/input/css/math-depth.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/css/media-query-serialization-basic.html b/Tests/LibWeb/Text/input/css/media-query-serialization-basic.html
index b0809751512..bfde83ee2fa 100644
--- a/Tests/LibWeb/Text/input/css/media-query-serialization-basic.html
+++ b/Tests/LibWeb/Text/input/css/media-query-serialization-basic.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <head><style>
 @media only screen { }
 @media only screen and (min-width: 20px) and (max-width: 40px) { }
diff --git a/Tests/LibWeb/Text/input/css/move-loaded-link-stylesheet-between-documents.html b/Tests/LibWeb/Text/input/css/move-loaded-link-stylesheet-between-documents.html
index 3db930dc7a7..9f9aff5311f 100644
--- a/Tests/LibWeb/Text/input/css/move-loaded-link-stylesheet-between-documents.html
+++ b/Tests/LibWeb/Text/input/css/move-loaded-link-stylesheet-between-documents.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     let doc = new DOMParser().parseFromString(`<link rel="stylesheet" href="data:text/css,div{}">`, `text/html`);
diff --git a/Tests/LibWeb/Text/input/css/revert-all.html b/Tests/LibWeb/Text/input/css/revert-all.html
index 7bb8767af20..05f23b00d0b 100644
--- a/Tests/LibWeb/Text/input/css/revert-all.html
+++ b/Tests/LibWeb/Text/input/css/revert-all.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <style>
 div { all: revert; }
 </style>
diff --git a/Tests/LibWeb/Text/input/css/sending-animationcancel-event-crash.html b/Tests/LibWeb/Text/input/css/sending-animationcancel-event-crash.html
index dfa5b6856c7..cf378e6f013 100644
--- a/Tests/LibWeb/Text/input/css/sending-animationcancel-event-crash.html
+++ b/Tests/LibWeb/Text/input/css/sending-animationcancel-event-crash.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <!-- https://github.com/SerenityOS/serenity/issues/24424 -->
 <style>
     @keyframes anim {
diff --git a/Tests/LibWeb/Text/input/css/set-style-declaration-shorthand.html b/Tests/LibWeb/Text/input/css/set-style-declaration-shorthand.html
index 540d3c7a7fc..d8e4f2bfced 100644
--- a/Tests/LibWeb/Text/input/css/set-style-declaration-shorthand.html
+++ b/Tests/LibWeb/Text/input/css/set-style-declaration-shorthand.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     function testFlexValue(value) {
diff --git a/Tests/LibWeb/Text/input/css/singular-percentage-calc-crash.html b/Tests/LibWeb/Text/input/css/singular-percentage-calc-crash.html
index 62a88bff93e..f30900c110c 100644
--- a/Tests/LibWeb/Text/input/css/singular-percentage-calc-crash.html
+++ b/Tests/LibWeb/Text/input/css/singular-percentage-calc-crash.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <style>
     div {
diff --git a/Tests/LibWeb/Text/input/css/small-aspect-ratio.html b/Tests/LibWeb/Text/input/css/small-aspect-ratio.html
index 5c5b20088f3..7de9331f0fe 100644
--- a/Tests/LibWeb/Text/input/css/small-aspect-ratio.html
+++ b/Tests/LibWeb/Text/input/css/small-aspect-ratio.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/css/string-serializes-with-quotes.html b/Tests/LibWeb/Text/input/css/string-serializes-with-quotes.html
index cb4cc5fc186..68054d962b6 100644
--- a/Tests/LibWeb/Text/input/css/string-serializes-with-quotes.html
+++ b/Tests/LibWeb/Text/input/css/string-serializes-with-quotes.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/css/style-declaration-parent-rule.html b/Tests/LibWeb/Text/input/css/style-declaration-parent-rule.html
index 36c9bdef673..f239488dec8 100644
--- a/Tests/LibWeb/Text/input/css/style-declaration-parent-rule.html
+++ b/Tests/LibWeb/Text/input/css/style-declaration-parent-rule.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <style>
 span {
     color: purple;
diff --git a/Tests/LibWeb/Text/input/css/style-sheet-with-byte-order-mark.html b/Tests/LibWeb/Text/input/css/style-sheet-with-byte-order-mark.html
index 12146cffd66..d8c86c82a40 100644
--- a/Tests/LibWeb/Text/input/css/style-sheet-with-byte-order-mark.html
+++ b/Tests/LibWeb/Text/input/css/style-sheet-with-byte-order-mark.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <head>
     <link rel="stylesheet" href="style-sheet-with-byte-order-mark.css" />
 </head>
diff --git a/Tests/LibWeb/Text/input/css/text-transform-dynamic-change.html b/Tests/LibWeb/Text/input/css/text-transform-dynamic-change.html
index 77b48e2cd84..c4c2988519d 100644
--- a/Tests/LibWeb/Text/input/css/text-transform-dynamic-change.html
+++ b/Tests/LibWeb/Text/input/css/text-transform-dynamic-change.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <style>
     #theDiv {
         width: max-content;
diff --git a/Tests/LibWeb/Text/input/css/transform-origin-serialization.html b/Tests/LibWeb/Text/input/css/transform-origin-serialization.html
index 3ac0a42bd77..d80a46d04d7 100644
--- a/Tests/LibWeb/Text/input/css/transform-origin-serialization.html
+++ b/Tests/LibWeb/Text/input/css/transform-origin-serialization.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/css/transform-serialization.html b/Tests/LibWeb/Text/input/css/transform-serialization.html
index 92a11fc4c3d..c62a81fdf7d 100644
--- a/Tests/LibWeb/Text/input/css/transform-serialization.html
+++ b/Tests/LibWeb/Text/input/css/transform-serialization.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/css/unicode-range-all-wildcard.html b/Tests/LibWeb/Text/input/css/unicode-range-all-wildcard.html
index 5ea5fd4aabb..b142385bdf3 100644
--- a/Tests/LibWeb/Text/input/css/unicode-range-all-wildcard.html
+++ b/Tests/LibWeb/Text/input/css/unicode-range-all-wildcard.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <style>
     @font-face {
         unicode-range: U+??;
diff --git a/Tests/LibWeb/Text/input/css/unknown-pseudo-elements-crash.html b/Tests/LibWeb/Text/input/css/unknown-pseudo-elements-crash.html
index 582ef65c89c..02ed4181b55 100644
--- a/Tests/LibWeb/Text/input/css/unknown-pseudo-elements-crash.html
+++ b/Tests/LibWeb/Text/input/css/unknown-pseudo-elements-crash.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/document-adopted-style-sheets.html b/Tests/LibWeb/Text/input/document-adopted-style-sheets.html
index f8bc245bd9b..5de883aa135 100644
--- a/Tests/LibWeb/Text/input/document-adopted-style-sheets.html
+++ b/Tests/LibWeb/Text/input/document-adopted-style-sheets.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <div id="testElement"></div>
 <script>
diff --git a/Tests/LibWeb/Text/input/document-scrollingElement-quirks-mode.html b/Tests/LibWeb/Text/input/document-scrollingElement-quirks-mode.html
index 2d187184ca0..09a1237c165 100644
--- a/Tests/LibWeb/Text/input/document-scrollingElement-quirks-mode.html
+++ b/Tests/LibWeb/Text/input/document-scrollingElement-quirks-mode.html
@@ -1,4 +1,4 @@
-<!-- quirks mode -->
+<!DOCTYPE quirks>
 <script src="include.js"></script>
 <script type="">
     test(() => {        
diff --git a/Tests/LibWeb/Text/input/failed-img-should-not-delay-load-event-forever.html b/Tests/LibWeb/Text/input/failed-img-should-not-delay-load-event-forever.html
index b67283b3a4a..2618e07b2c4 100644
--- a/Tests/LibWeb/Text/input/failed-img-should-not-delay-load-event-forever.html
+++ b/Tests/LibWeb/Text/input/failed-img-should-not-delay-load-event-forever.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <img src="invalid-protocol:foo">
 <script>
diff --git a/Tests/LibWeb/Text/input/fieldset-elements.html b/Tests/LibWeb/Text/input/fieldset-elements.html
index 401165f415d..07587f4cb8c 100644
--- a/Tests/LibWeb/Text/input/fieldset-elements.html
+++ b/Tests/LibWeb/Text/input/fieldset-elements.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="./include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/focus-contenteditable.html b/Tests/LibWeb/Text/input/focus-contenteditable.html
index 171c39eee62..f563e3066f0 100644
--- a/Tests/LibWeb/Text/input/focus-contenteditable.html
+++ b/Tests/LibWeb/Text/input/focus-contenteditable.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <style>
     #editable {
diff --git a/Tests/LibWeb/Text/input/focus-events.html b/Tests/LibWeb/Text/input/focus-events.html
index 0e4a938fead..4a54a708327 100644
--- a/Tests/LibWeb/Text/input/focus-events.html
+++ b/Tests/LibWeb/Text/input/focus-events.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <style>
     .input {
diff --git a/Tests/LibWeb/Text/input/form-formEnctype-attribute.html b/Tests/LibWeb/Text/input/form-formEnctype-attribute.html
index 87c640d673e..58bd32a1461 100644
--- a/Tests/LibWeb/Text/input/form-formEnctype-attribute.html
+++ b/Tests/LibWeb/Text/input/form-formEnctype-attribute.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="./include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/form-formMethod-attribute.html b/Tests/LibWeb/Text/input/form-formMethod-attribute.html
index 11d6f6e50ce..6e9ed1130cc 100644
--- a/Tests/LibWeb/Text/input/form-formMethod-attribute.html
+++ b/Tests/LibWeb/Text/input/form-formMethod-attribute.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="./include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/form-method-attribute.html b/Tests/LibWeb/Text/input/form-method-attribute.html
index 8e209409398..de64b2ffa9b 100644
--- a/Tests/LibWeb/Text/input/form-method-attribute.html
+++ b/Tests/LibWeb/Text/input/form-method-attribute.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="./include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/form-method-dialog.html b/Tests/LibWeb/Text/input/form-method-dialog.html
index 312419eb7c6..e48961d520e 100644
--- a/Tests/LibWeb/Text/input/form-method-dialog.html
+++ b/Tests/LibWeb/Text/input/form-method-dialog.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="./include.js"></script>
 <dialog id="test-dialog" open>
     <form method="dialog">
diff --git a/Tests/LibWeb/Text/input/geometry/dommatrix-create.html b/Tests/LibWeb/Text/input/geometry/dommatrix-create.html
index 270a5a198f7..1936079897d 100644
--- a/Tests/LibWeb/Text/input/geometry/dommatrix-create.html
+++ b/Tests/LibWeb/Text/input/geometry/dommatrix-create.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/geometry/dommatrix-flip.html b/Tests/LibWeb/Text/input/geometry/dommatrix-flip.html
index 93c407ca787..ca5a26e0784 100644
--- a/Tests/LibWeb/Text/input/geometry/dommatrix-flip.html
+++ b/Tests/LibWeb/Text/input/geometry/dommatrix-flip.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/geometry/dommatrix-matrix-value.html b/Tests/LibWeb/Text/input/geometry/dommatrix-matrix-value.html
index 45b5105a6f9..6e80268edc8 100644
--- a/Tests/LibWeb/Text/input/geometry/dommatrix-matrix-value.html
+++ b/Tests/LibWeb/Text/input/geometry/dommatrix-matrix-value.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/geometry/dommatrix-rotate.html b/Tests/LibWeb/Text/input/geometry/dommatrix-rotate.html
index 0ac110c663c..18d622808c8 100644
--- a/Tests/LibWeb/Text/input/geometry/dommatrix-rotate.html
+++ b/Tests/LibWeb/Text/input/geometry/dommatrix-rotate.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/geometry/dommatrix-scale.html b/Tests/LibWeb/Text/input/geometry/dommatrix-scale.html
index 353aba05a74..e390361b60f 100644
--- a/Tests/LibWeb/Text/input/geometry/dommatrix-scale.html
+++ b/Tests/LibWeb/Text/input/geometry/dommatrix-scale.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/geometry/dommatrix-skew.html b/Tests/LibWeb/Text/input/geometry/dommatrix-skew.html
index dcf736da9bb..738e1667bb1 100644
--- a/Tests/LibWeb/Text/input/geometry/dommatrix-skew.html
+++ b/Tests/LibWeb/Text/input/geometry/dommatrix-skew.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/geometry/dommatrix-to-array.html b/Tests/LibWeb/Text/input/geometry/dommatrix-to-array.html
index 8c17d634eb4..4ed066c1d6c 100644
--- a/Tests/LibWeb/Text/input/geometry/dommatrix-to-array.html
+++ b/Tests/LibWeb/Text/input/geometry/dommatrix-to-array.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/geometry/dommatrix-translate.html b/Tests/LibWeb/Text/input/geometry/dommatrix-translate.html
index 48a6559d285..204fa5519bf 100644
--- a/Tests/LibWeb/Text/input/geometry/dommatrix-translate.html
+++ b/Tests/LibWeb/Text/input/geometry/dommatrix-translate.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/geometry/dompoint.html b/Tests/LibWeb/Text/input/geometry/dompoint.html
index 9412a12e2d6..8fe8ba47a95 100644
--- a/Tests/LibWeb/Text/input/geometry/dompoint.html
+++ b/Tests/LibWeb/Text/input/geometry/dompoint.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/geometry/domquad.html b/Tests/LibWeb/Text/input/geometry/domquad.html
index d815cfa9b73..36eeb07a724 100644
--- a/Tests/LibWeb/Text/input/geometry/domquad.html
+++ b/Tests/LibWeb/Text/input/geometry/domquad.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/geometry/domrect-create.html b/Tests/LibWeb/Text/input/geometry/domrect-create.html
index 9a7c9b15362..2149f69c05d 100644
--- a/Tests/LibWeb/Text/input/geometry/domrect-create.html
+++ b/Tests/LibWeb/Text/input/geometry/domrect-create.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/geometry/legacy-window-alias.html b/Tests/LibWeb/Text/input/geometry/legacy-window-alias.html
index df842f7c538..368b368d1a2 100644
--- a/Tests/LibWeb/Text/input/geometry/legacy-window-alias.html
+++ b/Tests/LibWeb/Text/input/geometry/legacy-window-alias.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/getComputedStyle-grid-template-rows-columns.html b/Tests/LibWeb/Text/input/getComputedStyle-grid-template-rows-columns.html
index 55dfd8778ae..93f5f744a79 100644
--- a/Tests/LibWeb/Text/input/getComputedStyle-grid-template-rows-columns.html
+++ b/Tests/LibWeb/Text/input/getComputedStyle-grid-template-rows-columns.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <style>
     .grid-container {
diff --git a/Tests/LibWeb/Text/input/global-performance-property.html b/Tests/LibWeb/Text/input/global-performance-property.html
index 7641d2f2219..9822a49b3e7 100644
--- a/Tests/LibWeb/Text/input/global-performance-property.html
+++ b/Tests/LibWeb/Text/input/global-performance-property.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/hit_testing/basic.html b/Tests/LibWeb/Text/input/hit_testing/basic.html
index ab18d4cdee7..0ace0adad1d 100644
--- a/Tests/LibWeb/Text/input/hit_testing/basic.html
+++ b/Tests/LibWeb/Text/input/hit_testing/basic.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <style>
     * {
         border: 1px solid black;
diff --git a/Tests/LibWeb/Text/input/hit_testing/block-element-inside-inline-element.html b/Tests/LibWeb/Text/input/hit_testing/block-element-inside-inline-element.html
index 8ea1c293d21..a0957525291 100644
--- a/Tests/LibWeb/Text/input/hit_testing/block-element-inside-inline-element.html
+++ b/Tests/LibWeb/Text/input/hit_testing/block-element-inside-inline-element.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <style>
     * {
         font-family: sans-serif;
diff --git a/Tests/LibWeb/Text/input/hit_testing/inline-stacking-context.html b/Tests/LibWeb/Text/input/hit_testing/inline-stacking-context.html
index 5129e27f7aa..3365da117c8 100644
--- a/Tests/LibWeb/Text/input/hit_testing/inline-stacking-context.html
+++ b/Tests/LibWeb/Text/input/hit_testing/inline-stacking-context.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <style>
 span {
     z-index: 10;
diff --git a/Tests/LibWeb/Text/input/hit_testing/nested-inline-paintables.html b/Tests/LibWeb/Text/input/hit_testing/nested-inline-paintables.html
index 1b528968407..19f0f293993 100644
--- a/Tests/LibWeb/Text/input/hit_testing/nested-inline-paintables.html
+++ b/Tests/LibWeb/Text/input/hit_testing/nested-inline-paintables.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <body>
     <span id="outer">
diff --git a/Tests/LibWeb/Text/input/hit_testing/open-details-by-clicking-on-triangle.html b/Tests/LibWeb/Text/input/hit_testing/open-details-by-clicking-on-triangle.html
index 67ca58d7aaf..1f5862b2d2b 100644
--- a/Tests/LibWeb/Text/input/hit_testing/open-details-by-clicking-on-triangle.html
+++ b/Tests/LibWeb/Text/input/hit_testing/open-details-by-clicking-on-triangle.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <style>
     body {
         margin: 0;
diff --git a/Tests/LibWeb/Text/input/hit_testing/overflow-scroll.html b/Tests/LibWeb/Text/input/hit_testing/overflow-scroll.html
index 99f0183bbdb..af5735a0f41 100644
--- a/Tests/LibWeb/Text/input/hit_testing/overflow-scroll.html
+++ b/Tests/LibWeb/Text/input/hit_testing/overflow-scroll.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <style type="text/css">
     #container {
diff --git a/Tests/LibWeb/Text/input/hit_testing/pointer-events.html b/Tests/LibWeb/Text/input/hit_testing/pointer-events.html
index 6f41ad80384..a57a322052b 100644
--- a/Tests/LibWeb/Text/input/hit_testing/pointer-events.html
+++ b/Tests/LibWeb/Text/input/hit_testing/pointer-events.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <body>
     <!-- #a2 should be invisible to hit testing -->
diff --git a/Tests/LibWeb/Text/input/hit_testing/positioned-z-index-0-and-floats.html b/Tests/LibWeb/Text/input/hit_testing/positioned-z-index-0-and-floats.html
index baaae3c755e..755a7569693 100644
--- a/Tests/LibWeb/Text/input/hit_testing/positioned-z-index-0-and-floats.html
+++ b/Tests/LibWeb/Text/input/hit_testing/positioned-z-index-0-and-floats.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <style>
     #container {
diff --git a/Tests/LibWeb/Text/input/hit_testing/text.html b/Tests/LibWeb/Text/input/hit_testing/text.html
index 85a1e921a6b..cf3d61f9196 100644
--- a/Tests/LibWeb/Text/input/hit_testing/text.html
+++ b/Tests/LibWeb/Text/input/hit_testing/text.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <style>
     * {
         border: 1px solid black;
diff --git a/Tests/LibWeb/Text/input/html-form-controls-collection.html b/Tests/LibWeb/Text/input/html-form-controls-collection.html
index 27d3fb0867b..6f25da8f215 100644
--- a/Tests/LibWeb/Text/input/html-form-controls-collection.html
+++ b/Tests/LibWeb/Text/input/html-form-controls-collection.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <form>
   <input name="one" id="formcontrol" type="button" />
   <input name="two" id="formcontrol" type="text" />
diff --git a/Tests/LibWeb/Text/input/html-parser-text-in-table-hoisting.html b/Tests/LibWeb/Text/input/html-parser-text-in-table-hoisting.html
index 0eb5453663b..810a280323e 100644
--- a/Tests/LibWeb/Text/input/html-parser-text-in-table-hoisting.html
+++ b/Tests/LibWeb/Text/input/html-parser-text-in-table-hoisting.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <body><table><tr>PASS</tr></table></body>
 <script>
diff --git a/Tests/LibWeb/Text/input/http-reason-phrase-propagation.html b/Tests/LibWeb/Text/input/http-reason-phrase-propagation.html
index 92354b14ece..c14038cac2c 100644
--- a/Tests/LibWeb/Text/input/http-reason-phrase-propagation.html
+++ b/Tests/LibWeb/Text/input/http-reason-phrase-propagation.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="./include.js"></script>
 <script>
     asyncTest(async (done) => {
diff --git a/Tests/LibWeb/Text/input/idl-handling-of-null-attribute.html b/Tests/LibWeb/Text/input/idl-handling-of-null-attribute.html
index 8a1d3d3eaa0..78e68f95aa3 100644
--- a/Tests/LibWeb/Text/input/idl-handling-of-null-attribute.html
+++ b/Tests/LibWeb/Text/input/idl-handling-of-null-attribute.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <script id="script-element">
     test(() => {
diff --git a/Tests/LibWeb/Text/input/iframe-load-event-for-xml-src.html b/Tests/LibWeb/Text/input/iframe-load-event-for-xml-src.html
index 38da6383d22..080f879a941 100644
--- a/Tests/LibWeb/Text/input/iframe-load-event-for-xml-src.html
+++ b/Tests/LibWeb/Text/input/iframe-load-event-for-xml-src.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <iframe id="b" src="../data/document.xml"></iframe>
 <script>
diff --git a/Tests/LibWeb/Text/input/iframe-removed-asyncronously.html b/Tests/LibWeb/Text/input/iframe-removed-asyncronously.html
index fb0d904f507..92a30fd9f75 100644
--- a/Tests/LibWeb/Text/input/iframe-removed-asyncronously.html
+++ b/Tests/LibWeb/Text/input/iframe-removed-asyncronously.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <body>
 </body>
 <script src="include.js"></script>
diff --git a/Tests/LibWeb/Text/input/input-blur.html b/Tests/LibWeb/Text/input/input-blur.html
index 1fef4a10b91..f19abb8a285 100644
--- a/Tests/LibWeb/Text/input/input-blur.html
+++ b/Tests/LibWeb/Text/input/input-blur.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <input id=input type=text>
 <script src="include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/input-click-to-unfocus.html b/Tests/LibWeb/Text/input/input-click-to-unfocus.html
index 35efd99f6c7..55fc12233fd 100644
--- a/Tests/LibWeb/Text/input/input-click-to-unfocus.html
+++ b/Tests/LibWeb/Text/input/input-click-to-unfocus.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <input id=input type=text>
 <script src="include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/input-commit-on-unfocus.html b/Tests/LibWeb/Text/input/input-commit-on-unfocus.html
index a7ee207d0a8..8e5ef38fa79 100644
--- a/Tests/LibWeb/Text/input/input-commit-on-unfocus.html
+++ b/Tests/LibWeb/Text/input/input-commit-on-unfocus.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <input id=input type=text>
 <script src="include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/input-commit.html b/Tests/LibWeb/Text/input/input-commit.html
index c89c05e8c51..341b7d86de6 100644
--- a/Tests/LibWeb/Text/input/input-commit.html
+++ b/Tests/LibWeb/Text/input/input-commit.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <input id=input type=text>
 <script src="include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/input-date.html b/Tests/LibWeb/Text/input/input-date.html
index 97a13681777..0d926918334 100644
--- a/Tests/LibWeb/Text/input/input-date.html
+++ b/Tests/LibWeb/Text/input/input-date.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="./include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/input-element-file-value.html b/Tests/LibWeb/Text/input/input-element-file-value.html
index 4ee25c4171e..d425c82272c 100644
--- a/Tests/LibWeb/Text/input/input-element-file-value.html
+++ b/Tests/LibWeb/Text/input/input-element-file-value.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/input-file-accept.html b/Tests/LibWeb/Text/input/input-file-accept.html
index eb1a98781e4..eeb54c97361 100644
--- a/Tests/LibWeb/Text/input/input-file-accept.html
+++ b/Tests/LibWeb/Text/input/input-file-accept.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <input id="input1" type="file" accept="text/plain" />
 <input id="input2" type="file" accept="text/plain" multiple />
 <input id="input3" type="file" accept=".cpp" />
diff --git a/Tests/LibWeb/Text/input/input-file.html b/Tests/LibWeb/Text/input/input-file.html
index f569a13ec44..598c36ba717 100644
--- a/Tests/LibWeb/Text/input/input-file.html
+++ b/Tests/LibWeb/Text/input/input-file.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <input id="input1" type="file" />
 <input id="input2" type="file" multiple />
 <script src="./include.js"></script>
diff --git a/Tests/LibWeb/Text/input/input-image.html b/Tests/LibWeb/Text/input/input-image.html
index 10ecc5735e0..7616db8b7d0 100644
--- a/Tests/LibWeb/Text/input/input-image.html
+++ b/Tests/LibWeb/Text/input/input-image.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="./include.js"></script>
 <script type="text/javascript">
     const SOURCES = ["../../Assets/120.png", "file:///i-do-no-exist-i-swear.png"];
diff --git a/Tests/LibWeb/Text/input/input-maxlength.html b/Tests/LibWeb/Text/input/input-maxlength.html
index ed0a821faa0..0ff3ae2cd6e 100644
--- a/Tests/LibWeb/Text/input/input-maxlength.html
+++ b/Tests/LibWeb/Text/input/input-maxlength.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <input id="input" type="text" maxlength="5"><script src="include.js"></script><script>
     test(() => {
         const input = document.getElementById('input');
diff --git a/Tests/LibWeb/Text/input/input-number-float.html b/Tests/LibWeb/Text/input/input-number-float.html
index c2127b3b59b..18c338a4340 100644
--- a/Tests/LibWeb/Text/input/input-number-float.html
+++ b/Tests/LibWeb/Text/input/input-number-float.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <input id="input_number" type="number" />
 <script src="include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/input-number.html b/Tests/LibWeb/Text/input/input-number.html
index fda0e692725..7638a17fc89 100644
--- a/Tests/LibWeb/Text/input/input-number.html
+++ b/Tests/LibWeb/Text/input/input-number.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="./include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/input-readonly.html b/Tests/LibWeb/Text/input/input-readonly.html
index 44b07ce9bea..ffc09bd21db 100644
--- a/Tests/LibWeb/Text/input/input-readonly.html
+++ b/Tests/LibWeb/Text/input/input-readonly.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <input id=input type=text readonly><script src="include.js"></script><script>
     test(() => {
         const input = document.getElementById("input");
diff --git a/Tests/LibWeb/Text/input/input-value.html b/Tests/LibWeb/Text/input/input-value.html
index f47b6ae1374..c70dd0a2b08 100644
--- a/Tests/LibWeb/Text/input/input-value.html
+++ b/Tests/LibWeb/Text/input/input-value.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <input id="text" type="text" />
 <input id="hidden" type="hidden" />
 <input id="button" type="button" />
diff --git a/Tests/LibWeb/Text/input/internals.html b/Tests/LibWeb/Text/input/internals.html
index e05423e8b0b..d8998444818 100644
--- a/Tests/LibWeb/Text/input/internals.html
+++ b/Tests/LibWeb/Text/input/internals.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/invalid-transform-interpolation-does-not-crash.html b/Tests/LibWeb/Text/input/invalid-transform-interpolation-does-not-crash.html
index fe80297fa59..8edb954d5dd 100644
--- a/Tests/LibWeb/Text/input/invalid-transform-interpolation-does-not-crash.html
+++ b/Tests/LibWeb/Text/input/invalid-transform-interpolation-does-not-crash.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <div id="foo"></div>
 <script src="include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/is-collapsed.html b/Tests/LibWeb/Text/input/is-collapsed.html
index 5a12704953d..16f87a9a467 100644
--- a/Tests/LibWeb/Text/input/is-collapsed.html
+++ b/Tests/LibWeb/Text/input/is-collapsed.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <p id="a">Simply selectable</p>
 
diff --git a/Tests/LibWeb/Text/input/js-export-rename.html b/Tests/LibWeb/Text/input/js-export-rename.html
index f753053b39e..f710cfcfdcd 100644
--- a/Tests/LibWeb/Text/input/js-export-rename.html
+++ b/Tests/LibWeb/Text/input/js-export-rename.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <script>
     window.resultThingy = "FAIL";
diff --git a/Tests/LibWeb/Text/input/layout-tree-update/svg-use-invalidation-1.html b/Tests/LibWeb/Text/input/layout-tree-update/svg-use-invalidation-1.html
index db5b9ed3932..064f98a2f0c 100644
--- a/Tests/LibWeb/Text/input/layout-tree-update/svg-use-invalidation-1.html
+++ b/Tests/LibWeb/Text/input/layout-tree-update/svg-use-invalidation-1.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <svg><symbol id="foo"></symbol><use href="#foo"></use></svg>
 <script>
diff --git a/Tests/LibWeb/Text/input/link-element-media-attribute.html b/Tests/LibWeb/Text/input/link-element-media-attribute.html
index eb3a5013326..2fbebc9cb6f 100644
--- a/Tests/LibWeb/Text/input/link-element-media-attribute.html
+++ b/Tests/LibWeb/Text/input/link-element-media-attribute.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <style>
     body {
         background: green;
diff --git a/Tests/LibWeb/Text/input/link-element-onload-attribute.html b/Tests/LibWeb/Text/input/link-element-onload-attribute.html
index 30f1f51d072..b4b10b0f1e1 100644
--- a/Tests/LibWeb/Text/input/link-element-onload-attribute.html
+++ b/Tests/LibWeb/Text/input/link-element-onload-attribute.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <script>
     asyncTest(done => {
diff --git a/Tests/LibWeb/Text/input/link-element-rel-preload-load-event.html b/Tests/LibWeb/Text/input/link-element-rel-preload-load-event.html
index 7e72f79e0ea..0a40d37fefc 100644
--- a/Tests/LibWeb/Text/input/link-element-rel-preload-load-event.html
+++ b/Tests/LibWeb/Text/input/link-element-rel-preload-load-event.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <script>
     asyncTest(done => {
diff --git a/Tests/LibWeb/Text/input/link-element-search.html b/Tests/LibWeb/Text/input/link-element-search.html
index f815a628e2b..d46860eb2eb 100644
--- a/Tests/LibWeb/Text/input/link-element-search.html
+++ b/Tests/LibWeb/Text/input/link-element-search.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <a id="link-with-query" rel="search" href="https://serenityos.org/search?q=some:query"></a>
 <script src="include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/localStorage.html b/Tests/LibWeb/Text/input/localStorage.html
index 85fc7b4df29..109cc28b5b0 100644
--- a/Tests/LibWeb/Text/input/localStorage.html
+++ b/Tests/LibWeb/Text/input/localStorage.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/navigation/hashchange-event.html b/Tests/LibWeb/Text/input/navigation/hashchange-event.html
index 7d92aef3a1f..bbe9bfcb25a 100644
--- a/Tests/LibWeb/Text/input/navigation/hashchange-event.html
+++ b/Tests/LibWeb/Text/input/navigation/hashchange-event.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <iframe src="../../data/iframe-hashchange-event.html"></iframe>
 <script>
diff --git a/Tests/LibWeb/Text/input/navigation/history-popstate-event.html b/Tests/LibWeb/Text/input/navigation/history-popstate-event.html
index 6337a508fe3..d3f11486680 100644
--- a/Tests/LibWeb/Text/input/navigation/history-popstate-event.html
+++ b/Tests/LibWeb/Text/input/navigation/history-popstate-event.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <iframe src="../../data/iframe-popstate-event.html"></iframe>
 <script>
diff --git a/Tests/LibWeb/Text/input/navigation/history-pushstate.html b/Tests/LibWeb/Text/input/navigation/history-pushstate.html
index 4c09ff4548c..633aee1e2f1 100644
--- a/Tests/LibWeb/Text/input/navigation/history-pushstate.html
+++ b/Tests/LibWeb/Text/input/navigation/history-pushstate.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <iframe id="testIframe" src="about:blank"></iframe>
 <script>
diff --git a/Tests/LibWeb/Text/input/navigation/history-replace-push-state-race-2.html b/Tests/LibWeb/Text/input/navigation/history-replace-push-state-race-2.html
index dbbacdb520d..faeb0ad5616 100644
--- a/Tests/LibWeb/Text/input/navigation/history-replace-push-state-race-2.html
+++ b/Tests/LibWeb/Text/input/navigation/history-replace-push-state-race-2.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest(done => {
diff --git a/Tests/LibWeb/Text/input/navigation/history-replace-push-state-race-3.html b/Tests/LibWeb/Text/input/navigation/history-replace-push-state-race-3.html
index b1102c77f10..4cba65bad9c 100644
--- a/Tests/LibWeb/Text/input/navigation/history-replace-push-state-race-3.html
+++ b/Tests/LibWeb/Text/input/navigation/history-replace-push-state-race-3.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest(done => {
diff --git a/Tests/LibWeb/Text/input/navigation/history-replace-push-state-race.html b/Tests/LibWeb/Text/input/navigation/history-replace-push-state-race.html
index c735487f477..67cb4f064c2 100644
--- a/Tests/LibWeb/Text/input/navigation/history-replace-push-state-race.html
+++ b/Tests/LibWeb/Text/input/navigation/history-replace-push-state-race.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest(done => {
diff --git a/Tests/LibWeb/Text/input/navigation/iframe-navigate-javascript-url.html b/Tests/LibWeb/Text/input/navigation/iframe-navigate-javascript-url.html
index 80026357356..3f48c5dacde 100644
--- a/Tests/LibWeb/Text/input/navigation/iframe-navigate-javascript-url.html
+++ b/Tests/LibWeb/Text/input/navigation/iframe-navigate-javascript-url.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest((done) => {
diff --git a/Tests/LibWeb/Text/input/navigation/iframe-navigate-src.html b/Tests/LibWeb/Text/input/navigation/iframe-navigate-src.html
index 1248dfc4afd..2f67d99d596 100644
--- a/Tests/LibWeb/Text/input/navigation/iframe-navigate-src.html
+++ b/Tests/LibWeb/Text/input/navigation/iframe-navigate-src.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest(async done => {
diff --git a/Tests/LibWeb/Text/input/navigation/iframe-navigate-srcdoc.html b/Tests/LibWeb/Text/input/navigation/iframe-navigate-srcdoc.html
index 14057f1c5d8..b6644704cbc 100644
--- a/Tests/LibWeb/Text/input/navigation/iframe-navigate-srcdoc.html
+++ b/Tests/LibWeb/Text/input/navigation/iframe-navigate-srcdoc.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     asyncTest(async done => {
diff --git a/Tests/LibWeb/Text/input/navigation/iframe-unloading-order.html b/Tests/LibWeb/Text/input/navigation/iframe-unloading-order.html
index 93ffd572dfc..f173fc276dd 100644
--- a/Tests/LibWeb/Text/input/navigation/iframe-unloading-order.html
+++ b/Tests/LibWeb/Text/input/navigation/iframe-unloading-order.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <iframe id="iframe" src="../../data/iframe-unload-event.html"></iframe>
 <script>
diff --git a/Tests/LibWeb/Text/input/navigation/navigation-navigate.html b/Tests/LibWeb/Text/input/navigation/navigation-navigate.html
index ab0181d0a36..74531bbaeb1 100644
--- a/Tests/LibWeb/Text/input/navigation/navigation-navigate.html
+++ b/Tests/LibWeb/Text/input/navigation/navigation-navigate.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <iframe id="testIframe" src="about:blank"></iframe>
 <script>
diff --git a/Tests/LibWeb/Text/input/navigation/remove-iframe-from-timeout-callback.html b/Tests/LibWeb/Text/input/navigation/remove-iframe-from-timeout-callback.html
index e350dbfdf33..575f48594a7 100644
--- a/Tests/LibWeb/Text/input/navigation/remove-iframe-from-timeout-callback.html
+++ b/Tests/LibWeb/Text/input/navigation/remove-iframe-from-timeout-callback.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <div id="foo">
     <iframe></iframe>
diff --git a/Tests/LibWeb/Text/input/no-window-resize-on-load.html b/Tests/LibWeb/Text/input/no-window-resize-on-load.html
index f6f061b85b7..f4e5fdff76c 100644
--- a/Tests/LibWeb/Text/input/no-window-resize-on-load.html
+++ b/Tests/LibWeb/Text/input/no-window-resize-on-load.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script>
     var resizeCount = 0;
     onresize = function() {
diff --git a/Tests/LibWeb/Text/input/non-html-mixed-case-element-name-selector-matching.html b/Tests/LibWeb/Text/input/non-html-mixed-case-element-name-selector-matching.html
index 98fb7696a02..b34c898a95f 100644
--- a/Tests/LibWeb/Text/input/non-html-mixed-case-element-name-selector-matching.html
+++ b/Tests/LibWeb/Text/input/non-html-mixed-case-element-name-selector-matching.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <svg>
     <textPath></textPath>
diff --git a/Tests/LibWeb/Text/input/output-value.html b/Tests/LibWeb/Text/input/output-value.html
index 775149a0222..a1f5edcd2a8 100644
--- a/Tests/LibWeb/Text/input/output-value.html
+++ b/Tests/LibWeb/Text/input/output-value.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="./include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/performance-navigation.html b/Tests/LibWeb/Text/input/performance-navigation.html
index 4e69d67f3ba..55b803b8424 100644
--- a/Tests/LibWeb/Text/input/performance-navigation.html
+++ b/Tests/LibWeb/Text/input/performance-navigation.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/quirks-mode-case-insensitive-class-selector.html b/Tests/LibWeb/Text/input/quirks-mode-case-insensitive-class-selector.html
index a05eb820fe2..810a2666014 100644
--- a/Tests/LibWeb/Text/input/quirks-mode-case-insensitive-class-selector.html
+++ b/Tests/LibWeb/Text/input/quirks-mode-case-insensitive-class-selector.html
@@ -1,4 +1,4 @@
-<!-- Quirks mode -->
+<!DOCTYPE quirks>
 <script src="include.js"></script>
 <div class="tEsT"></div>
 <script>
diff --git a/Tests/LibWeb/Text/input/radio-node-list.html b/Tests/LibWeb/Text/input/radio-node-list.html
index 5a0e9489886..2de65a75427 100644
--- a/Tests/LibWeb/Text/input/radio-node-list.html
+++ b/Tests/LibWeb/Text/input/radio-node-list.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <form>
   <input value="value1" id="non-checked-with-value" type="radio"/>
   <input value="value2" id="non-checked-with-value" type="radio"/>
diff --git a/Tests/LibWeb/Text/input/regress/console-log-bogus-formatting-specifier.html b/Tests/LibWeb/Text/input/regress/console-log-bogus-formatting-specifier.html
index 80a777c6377..8ff058d802e 100644
--- a/Tests/LibWeb/Text/input/regress/console-log-bogus-formatting-specifier.html
+++ b/Tests/LibWeb/Text/input/regress/console-log-bogus-formatting-specifier.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="../include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/resize-scrollable-box.html b/Tests/LibWeb/Text/input/resize-scrollable-box.html
index 27487dbb698..430837f47d3 100644
--- a/Tests/LibWeb/Text/input/resize-scrollable-box.html
+++ b/Tests/LibWeb/Text/input/resize-scrollable-box.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <style>
     .scrollable-div {
         width: 100%;
diff --git a/Tests/LibWeb/Text/input/sameobject-behavior-for-htmlcollection-properties.html b/Tests/LibWeb/Text/input/sameobject-behavior-for-htmlcollection-properties.html
index 7cd174a8d7e..e1c56229e87 100644
--- a/Tests/LibWeb/Text/input/sameobject-behavior-for-htmlcollection-properties.html
+++ b/Tests/LibWeb/Text/input/sameobject-behavior-for-htmlcollection-properties.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <html>
 <form><table><thead><tr><td></td></tr></thead></table></form>
 <script src="include.js"></script>
diff --git a/Tests/LibWeb/Text/input/scripted-dom-insertion-during-html-parse.html b/Tests/LibWeb/Text/input/scripted-dom-insertion-during-html-parse.html
index 0f31386be8d..d459ea983ef 100644
--- a/Tests/LibWeb/Text/input/scripted-dom-insertion-during-html-parse.html
+++ b/Tests/LibWeb/Text/input/scripted-dom-insertion-during-html-parse.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <body></body>
 <script src="include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/scroll-into-view-center.html b/Tests/LibWeb/Text/input/scroll-into-view-center.html
index 08accabddab..b682aa3e16f 100644
--- a/Tests/LibWeb/Text/input/scroll-into-view-center.html
+++ b/Tests/LibWeb/Text/input/scroll-into-view-center.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <style>
     body {
diff --git a/Tests/LibWeb/Text/input/scroll-into-view-end.html b/Tests/LibWeb/Text/input/scroll-into-view-end.html
index 3eb4ff54c80..32de239e3bc 100644
--- a/Tests/LibWeb/Text/input/scroll-into-view-end.html
+++ b/Tests/LibWeb/Text/input/scroll-into-view-end.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <style>
     body {
diff --git a/Tests/LibWeb/Text/input/scroll-into-view-start.html b/Tests/LibWeb/Text/input/scroll-into-view-start.html
index 7fd69086872..7beb5bdb833 100644
--- a/Tests/LibWeb/Text/input/scroll-into-view-start.html
+++ b/Tests/LibWeb/Text/input/scroll-into-view-start.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <style>
     body {
diff --git a/Tests/LibWeb/Text/input/scroll-left-and-top-on-colgroup.html b/Tests/LibWeb/Text/input/scroll-left-and-top-on-colgroup.html
index 7c2c0464d17..f5521935cc4 100644
--- a/Tests/LibWeb/Text/input/scroll-left-and-top-on-colgroup.html
+++ b/Tests/LibWeb/Text/input/scroll-left-and-top-on-colgroup.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <table>
 <colgroup id="my-group">
 <col width="40">
diff --git a/Tests/LibWeb/Text/input/select-options-limit.html b/Tests/LibWeb/Text/input/select-options-limit.html
index 61d131d737b..df63442680d 100644
--- a/Tests/LibWeb/Text/input/select-options-limit.html
+++ b/Tests/LibWeb/Text/input/select-options-limit.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <select id="select"></select>
 
 <script src="include.js"></script>
diff --git a/Tests/LibWeb/Text/input/select-text.html b/Tests/LibWeb/Text/input/select-text.html
index 6e529752922..831af2a8aab 100644
--- a/Tests/LibWeb/Text/input/select-text.html
+++ b/Tests/LibWeb/Text/input/select-text.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <style>
     div {
diff --git a/Tests/LibWeb/Text/input/select.html b/Tests/LibWeb/Text/input/select.html
index b9ddf9edaa7..3c037cb6f20 100644
--- a/Tests/LibWeb/Text/input/select.html
+++ b/Tests/LibWeb/Text/input/select.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/selection-collapseToEnd.html b/Tests/LibWeb/Text/input/selection-collapseToEnd.html
index 623f1d150c9..2b647633e29 100644
--- a/Tests/LibWeb/Text/input/selection-collapseToEnd.html
+++ b/Tests/LibWeb/Text/input/selection-collapseToEnd.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <div>
     Well
diff --git a/Tests/LibWeb/Text/input/selection-extend-across-siblings.html b/Tests/LibWeb/Text/input/selection-extend-across-siblings.html
index dc61ee321b3..ad3e2ab2948 100644
--- a/Tests/LibWeb/Text/input/selection-extend-across-siblings.html
+++ b/Tests/LibWeb/Text/input/selection-extend-across-siblings.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <p id="p1">Well hello</p>
 <p id="p2">friends</p>
diff --git a/Tests/LibWeb/Text/input/selection-extend-backwards.html b/Tests/LibWeb/Text/input/selection-extend-backwards.html
index 02722e311a0..dcf88ae731c 100644
--- a/Tests/LibWeb/Text/input/selection-extend-backwards.html
+++ b/Tests/LibWeb/Text/input/selection-extend-backwards.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <p id="a">Uno</p>
 
diff --git a/Tests/LibWeb/Text/input/selectionchange-event.html b/Tests/LibWeb/Text/input/selectionchange-event.html
index b3b1fb8dbbe..0e8c6c39bf0 100644
--- a/Tests/LibWeb/Text/input/selectionchange-event.html
+++ b/Tests/LibWeb/Text/input/selectionchange-event.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <style>
     #editable {
diff --git a/Tests/LibWeb/Text/input/set-selection-inside-shadow-root.html b/Tests/LibWeb/Text/input/set-selection-inside-shadow-root.html
index df03d6afe72..1434cc5f313 100644
--- a/Tests/LibWeb/Text/input/set-selection-inside-shadow-root.html
+++ b/Tests/LibWeb/Text/input/set-selection-inside-shadow-root.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <div id="root"></div>
 <script>
diff --git a/Tests/LibWeb/Text/input/set-timeout-with-no-active-script.html b/Tests/LibWeb/Text/input/set-timeout-with-no-active-script.html
index 1115bd28893..827d538a126 100644
--- a/Tests/LibWeb/Text/input/set-timeout-with-no-active-script.html
+++ b/Tests/LibWeb/Text/input/set-timeout-with-no-active-script.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/setInterval.html b/Tests/LibWeb/Text/input/setInterval.html
index d7e2c9121bd..c764c269f2f 100644
--- a/Tests/LibWeb/Text/input/setInterval.html
+++ b/Tests/LibWeb/Text/input/setInterval.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <script>
     asyncTest(done => {
diff --git a/Tests/LibWeb/Text/input/setTimeout.html b/Tests/LibWeb/Text/input/setTimeout.html
index 0b6a7b83789..6b8564bf519 100644
--- a/Tests/LibWeb/Text/input/setTimeout.html
+++ b/Tests/LibWeb/Text/input/setTimeout.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <script>
     asyncTest(done => {
diff --git a/Tests/LibWeb/Text/input/setting-display-none-should-nuke-subtree.html b/Tests/LibWeb/Text/input/setting-display-none-should-nuke-subtree.html
index 9e9f0933970..d0a508360dd 100644
--- a/Tests/LibWeb/Text/input/setting-display-none-should-nuke-subtree.html
+++ b/Tests/LibWeb/Text/input/setting-display-none-should-nuke-subtree.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/shadow-root-adopted-style-sheets.html b/Tests/LibWeb/Text/input/shadow-root-adopted-style-sheets.html
index 492f2d9a920..9959fd79f82 100644
--- a/Tests/LibWeb/Text/input/shadow-root-adopted-style-sheets.html
+++ b/Tests/LibWeb/Text/input/shadow-root-adopted-style-sheets.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <style>
     #test {
diff --git a/Tests/LibWeb/Text/input/shadow-root-style-sheets.html b/Tests/LibWeb/Text/input/shadow-root-style-sheets.html
index 7b1d361a248..731d93f324d 100644
--- a/Tests/LibWeb/Text/input/shadow-root-style-sheets.html
+++ b/Tests/LibWeb/Text/input/shadow-root-style-sheets.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <my-custom-element></my-custom-element>
 <script>
diff --git a/Tests/LibWeb/Text/input/show-non-modal-dialog.html b/Tests/LibWeb/Text/input/show-non-modal-dialog.html
index 19ceb7d6000..5fcb959bc65 100644
--- a/Tests/LibWeb/Text/input/show-non-modal-dialog.html
+++ b/Tests/LibWeb/Text/input/show-non-modal-dialog.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="./include.js"></script>
 <dialog id="test-dialog"></dialog>
 <script>
diff --git a/Tests/LibWeb/Text/input/synthetic-event-constructor-istrusted-check.html b/Tests/LibWeb/Text/input/synthetic-event-constructor-istrusted-check.html
index 6af2c485cb4..a2fb6c98a6a 100644
--- a/Tests/LibWeb/Text/input/synthetic-event-constructor-istrusted-check.html
+++ b/Tests/LibWeb/Text/input/synthetic-event-constructor-istrusted-check.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/table-cell-without-table-ancestor.html b/Tests/LibWeb/Text/input/table-cell-without-table-ancestor.html
index 4d8af8802c1..d08bfc8969e 100644
--- a/Tests/LibWeb/Text/input/table-cell-without-table-ancestor.html
+++ b/Tests/LibWeb/Text/input/table-cell-without-table-ancestor.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <body>
     <script src="include.js"></script>
     <script>
diff --git a/Tests/LibWeb/Text/input/test-http-test-server.html b/Tests/LibWeb/Text/input/test-http-test-server.html
index 46a213b0d7d..290887fdcbc 100644
--- a/Tests/LibWeb/Text/input/test-http-test-server.html
+++ b/Tests/LibWeb/Text/input/test-http-test-server.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="./include.js"></script>
 <script>
     asyncTest(async (done) => {
diff --git a/Tests/LibWeb/Text/input/textarea-maxlength.html b/Tests/LibWeb/Text/input/textarea-maxlength.html
index cda3e643de7..87362140141 100644
--- a/Tests/LibWeb/Text/input/textarea-maxlength.html
+++ b/Tests/LibWeb/Text/input/textarea-maxlength.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <textarea id="textarea" maxlength="5"></textarea><script src="include.js"></script><script>
     test(() => {
         const textarea = document.getElementById('textarea');
diff --git a/Tests/LibWeb/Text/input/textarea-readonly.html b/Tests/LibWeb/Text/input/textarea-readonly.html
index ca6d253c72b..abf08140c03 100644
--- a/Tests/LibWeb/Text/input/textarea-readonly.html
+++ b/Tests/LibWeb/Text/input/textarea-readonly.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <textarea id=textarea readonly></textarea><script src="include.js"></script><script>
     test(() => {
         const textarea = document.getElementById("textarea");
diff --git a/Tests/LibWeb/Text/input/textarea-selection-start-selection-end.html b/Tests/LibWeb/Text/input/textarea-selection-start-selection-end.html
index 00aadd9015f..5e5598e0bed 100644
--- a/Tests/LibWeb/Text/input/textarea-selection-start-selection-end.html
+++ b/Tests/LibWeb/Text/input/textarea-selection-start-selection-end.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <textarea id="textarea"></textarea>
 <script src="include.js"></script>
 <script type="text/javascript">
diff --git a/Tests/LibWeb/Text/input/textarea-value.html b/Tests/LibWeb/Text/input/textarea-value.html
index 3efe7f1988c..e38731ff336 100644
--- a/Tests/LibWeb/Text/input/textarea-value.html
+++ b/Tests/LibWeb/Text/input/textarea-value.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/title-with-meta-title.html b/Tests/LibWeb/Text/input/title-with-meta-title.html
index 825366d0511..66a2774b2e2 100644
--- a/Tests/LibWeb/Text/input/title-with-meta-title.html
+++ b/Tests/LibWeb/Text/input/title-with-meta-title.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <head>
     <title>foo</title>
     <meta name="title" content="bar" />
diff --git a/Tests/LibWeb/Text/input/title.html b/Tests/LibWeb/Text/input/title.html
index b394665d859..59465bb3efe 100644
--- a/Tests/LibWeb/Text/input/title.html
+++ b/Tests/LibWeb/Text/input/title.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/unclosed-body-element.html b/Tests/LibWeb/Text/input/unclosed-body-element.html
index 0466b1b51ea..80aeda67d45 100644
--- a/Tests/LibWeb/Text/input/unclosed-body-element.html
+++ b/Tests/LibWeb/Text/input/unclosed-body-element.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <div>
 <body
 <pre>
diff --git a/Tests/LibWeb/Text/input/unclosed-html-element.html b/Tests/LibWeb/Text/input/unclosed-html-element.html
index ca3860248f6..429ddba56ed 100644
--- a/Tests/LibWeb/Text/input/unclosed-html-element.html
+++ b/Tests/LibWeb/Text/input/unclosed-html-element.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <link>
 <html
 <head>
diff --git a/Tests/LibWeb/Text/input/video-canceled-load.html b/Tests/LibWeb/Text/input/video-canceled-load.html
index fd5aaa647d0..174defea640 100644
--- a/Tests/LibWeb/Text/input/video-canceled-load.html
+++ b/Tests/LibWeb/Text/input/video-canceled-load.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <script type="text/javascript">
     function updateSrc() {
diff --git a/Tests/LibWeb/Text/input/video-failed-load.html b/Tests/LibWeb/Text/input/video-failed-load.html
index c353335cf80..164c0b55574 100644
--- a/Tests/LibWeb/Text/input/video-failed-load.html
+++ b/Tests/LibWeb/Text/input/video-failed-load.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <script type="text/javascript">
     const SOURCES = [
diff --git a/Tests/LibWeb/Text/input/video-gc.html b/Tests/LibWeb/Text/input/video-gc.html
index 8c241b7f7e7..d038ab43309 100644
--- a/Tests/LibWeb/Text/input/video-gc.html
+++ b/Tests/LibWeb/Text/input/video-gc.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <iframe id="iframe"></iframe>
 <script src="include.js"></script>
 <script>
diff --git a/Tests/LibWeb/Text/input/window-event-property-setter.html b/Tests/LibWeb/Text/input/window-event-property-setter.html
index eafca73ccc9..f7a39f6693f 100644
--- a/Tests/LibWeb/Text/input/window-event-property-setter.html
+++ b/Tests/LibWeb/Text/input/window-event-property-setter.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/window-proxy-numeric-own-property.html b/Tests/LibWeb/Text/input/window-proxy-numeric-own-property.html
index ae61ba3cad3..c66a9388f80 100644
--- a/Tests/LibWeb/Text/input/window-proxy-numeric-own-property.html
+++ b/Tests/LibWeb/Text/input/window-proxy-numeric-own-property.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <iframe src="about:blank"></iframe>
 <script>
diff --git a/Tests/LibWeb/Text/input/window-proxy-property-inline-cache.html b/Tests/LibWeb/Text/input/window-proxy-property-inline-cache.html
index af005f95615..b3c83699c99 100644
--- a/Tests/LibWeb/Text/input/window-proxy-property-inline-cache.html
+++ b/Tests/LibWeb/Text/input/window-proxy-property-inline-cache.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <script src="include.js"></script>
 <script>
     test(() => {
diff --git a/Tests/LibWeb/Text/input/window-scroll-while-parsing.html b/Tests/LibWeb/Text/input/window-scroll-while-parsing.html
index d7adf3a8141..c557cf63fb6 100644
--- a/Tests/LibWeb/Text/input/window-scroll-while-parsing.html
+++ b/Tests/LibWeb/Text/input/window-scroll-while-parsing.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <body>
     <script>
         window.scrollTo(200, 200);
diff --git a/Tests/LibWeb/Text/input/window-scrollTo.html b/Tests/LibWeb/Text/input/window-scrollTo.html
index 728e9382753..0675aa8b91c 100644
--- a/Tests/LibWeb/Text/input/window-scrollTo.html
+++ b/Tests/LibWeb/Text/input/window-scrollTo.html
@@ -1,3 +1,4 @@
+<!DOCTYPE html>
 <style>
     div {
         width: 1000px;
