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 34 0+0+0] [BFC] children: not-inline
    BlockContainer <body> at [8,8] [8+0+0 784 0+0+8] [8+0+0 18 0+0+8] children: inline
      frag 0 from BlockContainer start: 0, length: 0, rect: [13,19 0x0] baseline: 4
      BlockContainer <button> at [13,19] inline-block [0+1+4 0 4+1+0] [0+1+1 0 1+1+0] [BFC] children: not-inline
        BlockContainer <(anonymous)> at [13,19] flex-container(column) [0+0+0 0 0+0+0] [0+0+0 0 0+0+0] [FFC] children: not-inline
          BlockContainer <(anonymous)> at [13,19] inline-block [0+0+0 0 0+0+0] [0+0+0 0 0+0+0] [BFC] children: not-inline

ViewportPaintable (Viewport<#document>) [0,0 800x600]
  PaintableWithLines (BlockContainer<HTML>) [0,0 800x34]
    PaintableWithLines (BlockContainer<BODY>) [8,8 784x18]
      PaintableWithLines (BlockContainer<BUTTON>) [8,17 10x4]
        PaintableWithLines (BlockContainer(anonymous)) [13,19 0x0]
          PaintableWithLines (BlockContainer(anonymous)) [13,19 0x0]

SC for Viewport<#document> [0,0 800x600] [children: 1] (z-index: auto)
 SC for BlockContainer<HTML> [0,0 800x34] [children: 0] (z-index: auto)
