Viewport <#document> at (0,0) content-size 800x600 children: not-inline
  BlockContainer <html> at (0,0) content-size 800x0 [BFC] children: not-inline
    BlockContainer <body> at (8,8) content-size 140x100 positioned [BFC] children: not-inline
      BlockContainer <div.black> at (58,58) content-size 40x0 children: inline
        BlockContainer <div.green> at (78,78) content-size 0x0 floating [BFC] children: not-inline
        TextNode <#text>
