Viewport <#document> at [0,0] [0+0+0 800 0+0+0] [0+0+0 600 0+0+0] [BFC] children: not-inline
  BlockContainer <html> at [0,0] [0+0+0 800 0+0+0] [0+0+0 16 0+0+0] [BFC] children: not-inline
    Box <body> at [8,8] flex-container(column) [8+0+0 0 0+0+792] [8+0+0 0 0+0+8] [FFC] children: not-inline

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

SC for Viewport<#document> [0,0 800x600] [children: 1] (z-index: auto)
 SC for BlockContainer<HTML> [0,0 800x16] [children: 0] (z-index: auto)
