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 [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: not-inline
      BlockContainer <details> at [8,8] [0+0+0 784 0+0+0] [0+0+0 18 0+0+0] children: not-inline
        ListItemBox <summary> at [24,8] [0+0+0 776 0+0+0] [0+0+0 18 0+0+0] children: inline
          frag 0 from TextNode start: 0, length: 13, rect: [24,8 114.625x18] baseline: 13.796875
              "I'm a summary"
          ListItemMarkerBox <(anonymous)> at [8,13] [0+0+0 8 0+0+0] [0+0+0 8 0+0+0] children: not-inline
          TextNode <#text> (not painted)
        BlockContainer <slot> at [8,34] [0+0+0 784 0+0+0] [0+0+0 0 0+0+0] children: not-inline
      BlockContainer <(anonymous)> at [8,26] [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 800x34]
    PaintableWithLines (BlockContainer<BODY>) [8,8 784x18] overflow: [8,8 792x18]
      PaintableWithLines (BlockContainer<DETAILS>) [8,8 784x18] overflow: [8,8 792x18]
        PaintableWithLines (ListItemBox<SUMMARY>) [24,8 776x18]
          MarkerPaintable (ListItemMarkerBox(anonymous)) [8,13 8x8]
          TextPaintable (TextNode<#text>)
        PaintableWithLines (BlockContainer<SLOT>) [8,34 784x0]
      PaintableWithLines (BlockContainer(anonymous)) [8,26 784x0]

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