Viewport <#document> at [0,0] [0+0+0 800 0+0+0] [0+0+0 600 0+0+0] children: not-inline
  BlockContainer <html> at [1,1] [0+1+0 798 0+1+0] [0+1+0 120 0+1+0] [BFC] children: not-inline
    BlockContainer <body> at [10,10] [8+1+0 54 0+1+734] [8+1+0 102 0+1+8] children: not-inline
      Box <div.flex> at [11,11] flex-container(column) [0+1+0 52 0+1+0] [0+1+0 100 0+1+0] [FFC] children: not-inline
        BlockContainer <div.hmm> at [12,12] flex-item [0+1+0 50 0+1+0] [0+1+0 18 0+1+0] [BFC] children: inline
          frag 0 from TextNode start: 0, length: 5, rect: [12,12 39.78125x18] baseline: 13.796875
              "Hello"
          TextNode <#text> (not painted)
        BlockContainer <(anonymous)> (not painted) [BFC] children: inline
          TextNode <#text> (not painted)

ViewportPaintable (Viewport<#document>) [0,0 800x600]
  PaintableWithLines (BlockContainer<HTML>) [0,0 800x122]
    PaintableWithLines (BlockContainer<BODY>) [9,9 56x104]
      PaintableBox (Box<DIV>.flex) [10,10 54x102]
        PaintableWithLines (BlockContainer<DIV>.hmm) [11,11 52x20]
          TextPaintable (TextNode<#text>)

SC for Viewport<#document> [0,0 800x600] [children: 1] (z-index: auto)
 SC for BlockContainer<HTML> [1,1 798x120] [children: 0] (z-index: auto)
