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 32 0+0+0] [BFC] children: not-inline
    BlockContainer <body> at [8,8] [8+0+0 784 0+0+8] [8+0+0 16 0+0+8] children: not-inline
      BlockContainer <details> at [8,8] [0+0+0 784 0+0+0] [0+0+0 16 0+0+0] children: not-inline
        ListItemBox <summary> at [8,8] [0+0+0 784 0+0+0] [0+0+0 16 0+0+0] children: inline
          frag 0 from ListItemMarkerBox start: 0, length: 0, rect: [8,8 13.84375x16] baseline: 12.796875
          frag 1 from TextNode start: 0, length: 13, rect: [21.84375,8 114.625x16] baseline: 12.796875
              "I'm a summary"
          ListItemMarkerBox <(anonymous)> at [8,8] [0+0+0 13.84375 0+0+0] [0+0+0 16 0+0+0] [BFC] children: inline
            frag 0 from GeneratedTextNode start: 0, length: 2, rect: [8,8 13.84375x16] baseline: 12.796875
                "▸ "
            GeneratedTextNode <(anonymous)> (not painted)
          TextNode <#text> (not painted)
        BlockContainer <slot> at [8,24] [0+0+0 784 0+0+0] [0+0+0 0 0+0+0] children: not-inline
      BlockContainer <(anonymous)> at [8,24] [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 800x32]
    PaintableWithLines (BlockContainer<BODY>) [8,8 784x16]
      PaintableWithLines (BlockContainer<DETAILS>) [8,8 784x16]
        PaintableWithLines (ListItemBox<SUMMARY>) [8,8 784x16]
          PaintableWithLines (ListItemMarkerBox(anonymous)) [8,8 13.84375x16]
        PaintableWithLines (BlockContainer<SLOT>) [8,24 784x0]
      PaintableWithLines (BlockContainer(anonymous)) [8,24 784x0]

SC for Viewport<#document> [0,0 800x600] (z-index: auto)
 SC for BlockContainer<HTML> [0,0 800x32] (z-index: auto)
