Viewport <#document> at [0,0] [0+0+0 800 0+0+0] [0+0+0 600 0+0+0] [BFC] children: not-inline
BlockContainer at [0,0] [0+0+0 800 0+0+0] [0+0+0 0 0+0+0] [BFC] children: not-inline
Box
at [8,8] positioned flex-container(row) [8+0+0 31.15625 0+0+8] [8+0+0 300 0+0+8] [FFC] children: not-inline
BlockContainer at [8,8] flex-item [0+0+0 31.15625 0+0+0] [0+0+0 300 0+0+0] [BFC] children: inline
frag 0 from TextNode start: 0, length: 3, rect: [8,8 31.15625x18] baseline: 13.796875
"Sup"
TextNode <#text> (not painted)
ViewportPaintable (Viewport<#document>) [0,0 800x600]
PaintableWithLines (BlockContainer) [0,0 800x0]
PaintableBox (Box) [8,8 31.15625x300]
PaintableWithLines (BlockContainer
) [8,8 31.15625x300]
TextPaintable (TextNode<#text>)
SC for Viewport<#document> [0,0 800x600] [children: 1] (z-index: auto)
SC for BlockContainer [0,0 800x0] [children: 0] (z-index: auto)