Viewport <#document> at (0,0) content-size 800x600 children: not-inline
  BlockContainer <html> at (0,0) content-size 800x136 [BFC] children: not-inline
    BlockContainer <body> at (18,18) content-size 764x100 children: not-inline
      BlockContainer <div.box> at (18,18) content-size 100x100 children: not-inline

ViewportPaintable (Viewport<#document>) [0,0 800x600]
  PaintableWithLines (BlockContainer<HTML>) [0,0 800x136]
    PaintableWithLines (BlockContainer<BODY>) [8,8 784x120]
      PaintableWithLines (BlockContainer<DIV>.box) [18,18 100x100]
