Viewport <#document> at (0,0) content-size 800x600 children: not-inline
  Box <html> at (0,0) content-size 800x16 [GFC] children: not-inline
    BlockContainer <body> at (8,8) content-size 184x0 [BFC] children: not-inline

ViewportPaintable (Viewport<#document>) [0,0 800x600]
  PaintableBox (Box<HTML>) [0,0 800x16]
    PaintableWithLines (BlockContainer<BODY>) [8,8 184x0]
