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  BlockContainer <html> at (0,0) content-size 800x33.46875 [BFC] children: not-inline
    Box <body.outer> at (8,8) content-size 200x17.46875 flex-container(column) [FFC] children: not-inline
      BlockContainer <div.middle> at (8,8) content-size 200x17.46875 flex-item [BFC] children: not-inline
        BlockContainer <div.inner> at (8,8) content-size 200x17.46875 children: inline
          line 0 width: 174.234375, height: 17.46875, bottom: 17.46875, baseline: 13.53125
            frag 0 from TextNode start: 0, length: 20, rect: [8,8 174.234375x17.46875]
              "percentages are hard"
          TextNode <#text>
