Viewport <#document> at (0,0) content-size 800x600 children: not-inline
  BlockContainer <html> at (0,0) content-size 800x116 [BFC] children: not-inline
    Box <body> at (8,8) content-size 784x100 flex-container(column) [FFC] children: not-inline
      BlockContainer <div> at (8,8) content-size 100x100 flex-item [BFC] children: not-inline

ViewportPaintable (Viewport<#document>) [0,0 800x600]
  PaintableWithLines (BlockContainer<HTML>) [0,0 800x116]
    PaintableBox (Box<BODY>) [8,8 784x100]
      PaintableWithLines (BlockContainer<DIV>) [8,8 100x100]
