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+0 400 0+0+400] [0+0+0 400 0+0+0] [BFC] children: not-inline
    Box <body> at [8,8] flex-container(column) [8+0+0 400 0+0+-8] [8+0+0 200 0+0+8] [FFC] children: not-inline
      BlockContainer <main> at [8,8] flex-item [0+0+0 300 0+0+0] [0+0+0 200 0+0+0] [BFC] children: not-inline
        BlockContainer <article> at [8,8] [0+0+0 300 0+0+0] [0+0+0 200 0+0+0] children: not-inline

ViewportPaintable (Viewport<#document>) [0,0 800x600]
  PaintableWithLines (BlockContainer<HTML>) [0,0 400x400]
    PaintableBox (Box<BODY>) [8,8 400x200]
      PaintableWithLines (BlockContainer<MAIN>) [8,8 300x200]
        PaintableWithLines (BlockContainer<ARTICLE>) [8,8 300x200]

SC for Viewport<#document> [0,0 800x600] (z-index: auto)
 SC for BlockContainer<HTML> [0,0 400x400] (z-index: auto)
