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 52 0+0+0] [BFC] children: not-inline
    BlockContainer <body> at [8,8] [8+0+0 784 0+0+8] [8+0+0 36 0+0+8] children: not-inline
      BlockContainer <input.btn> at [13,10] [0+1+4 195.796875 4+1+578.203125] [0+1+1 32 1+1+0] children: not-inline
        BlockContainer <(anonymous)> at [13,10] flex-container(column) [0+0+0 195.796875 0+0+0] [0+0+0 32 0+0+0] [FFC] children: not-inline
          BlockContainer <(anonymous)> at [13,17.5] flex-item [0+0+0 195.796875 0+0+0] [0+0+0 17 0+0+0] [BFC] children: inline
            frag 0 from BlockContainer start: 0, length: 0, rect: [13,17.5 195.796875x17] baseline: 13
            BlockContainer <span> at [13,17.5] inline-block [0+0+0 195.796875 0+0+0] [0+0+0 17 0+0+0] [BFC] children: inline
              frag 0 from TextNode start: 0, length: 26, rect: [13,17.5 195.796875x17] baseline: 13
                  "Width should shrink to fit"
              TextNode <#text> (not painted)
      BlockContainer <(anonymous)> at [8,44] [0+0+0 784 0+0+0] [0+0+0 0 0+0+0] children: inline
        TextNode <#text> (not painted)

ViewportPaintable (Viewport<#document>) [0,0 800x600]
  PaintableWithLines (BlockContainer<HTML>) [0,0 800x52]
    PaintableWithLines (BlockContainer<BODY>) [8,8 784x36]
      PaintableWithLines (BlockContainer<INPUT>.btn) [8,8 205.796875x36]
        PaintableWithLines (BlockContainer(anonymous)) [13,10 195.796875x32]
          PaintableWithLines (BlockContainer(anonymous)) [13,17.5 195.796875x17]
            PaintableWithLines (BlockContainer<SPAN>) [13,17.5 195.796875x17]
              TextPaintable (TextNode<#text>)
      PaintableWithLines (BlockContainer(anonymous)) [8,44 784x0]

SC for Viewport<#document> [0,0 800x600] [children: 1] (z-index: auto)
 SC for BlockContainer<HTML> [0,0 800x52] [children: 0] (z-index: auto)
