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 784x36 children: not-inline
      BlockContainer <details> at (8,8) content-size 784x36 children: not-inline
        ListItemBox <summary> at (32,8) content-size 760x18 children: inline
          frag 0 from TextNode start: 0, length: 13, rect: [32,8 114.625x18] baseline: 13.796875
              "I'm a summary"
          ListItemMarkerBox <(anonymous)> at (8,8.5) content-size 12x17 children: not-inline
          TextNode <#text>
        BlockContainer <slot> at (8,26) content-size 784x18 children: inline
          TextNode <#text>
          TextNode <#text>
          InlineNode <span>
            frag 0 from TextNode start: 0, length: 10, rect: [8,26 82.3125x18] baseline: 13.796875
                "I'm a node"
            TextNode <#text>
          TextNode <#text>
      BlockContainer <(anonymous)> at (8,44) content-size 784x0 children: inline
        TextNode <#text>

ViewportPaintable (Viewport<#document>) [0,0 800x600]
  PaintableWithLines (BlockContainer<HTML>) [0,0 800x600]
    PaintableWithLines (BlockContainer<BODY>) [8,8 784x36]
      PaintableWithLines (BlockContainer<DETAILS>) [8,8 784x36]
        PaintableWithLines (ListItemBox<SUMMARY>) [32,8 760x18]
          MarkerPaintable (ListItemMarkerBox(anonymous)) [8,8.5 12x17]
          TextPaintable (TextNode<#text>)
        PaintableWithLines (BlockContainer<SLOT>) [8,26 784x18]
          PaintableWithLines (InlineNode<SPAN>)
            TextPaintable (TextNode<#text>)
      PaintableWithLines (BlockContainer(anonymous)) [8,44 784x0]
