Viewport <#document> at (0,0) content-size 800x600 children: not-inline
  BlockContainer <html> at (0,0) content-size 800x600 [BFC] children: not-inline
    BlockContainer <body> at (8,8) content-size 784x59 children: inline
      frag 0 from BlockContainer start: 0, length: 0, rect: [13,10 111.65625x55] baseline: 43.890625
      BlockContainer <button> at (13,10) content-size 111.65625x55 inline-block [BFC] children: not-inline
        BlockContainer <(anonymous)> at (13,10) content-size 111.65625x55 flex-container(column) [FFC] children: not-inline
          BlockContainer <(anonymous)> at (13,10) content-size 111.65625x55 flex-item [BFC] children: inline
            frag 0 from TextNode start: 0, length: 4, rect: [13,10 111.65625x55] baseline: 41.890625
                "Test"
            TextNode <#text>

ViewportPaintable (Viewport<#document>) [0,0 800x600]
  PaintableWithLines (BlockContainer<HTML>) [0,0 800x600]
    PaintableWithLines (BlockContainer<BODY>) [8,8 784x59]
      PaintableWithLines (BlockContainer<BUTTON>) [8,8 121.65625x59]
        PaintableWithLines (BlockContainer(anonymous)) [13,10 111.65625x55]
          PaintableWithLines (BlockContainer(anonymous)) [13,10 111.65625x55]
            TextPaintable (TextNode<#text>)
