layer at (0,0) size 800x600
  RenderCanvas at (0,0) size 800x600
layer at (0,0) size 800x40
  RenderBlock {HTML} at (0,0) size 800x40
    RenderBody {BODY} at (8,8) size 784x18
      RenderBlock {P} at (0,0) size 784x18
        RenderText {TEXT} at (0,0) size 288x17
          text run at (0,0) width 288: "Nothing should appear below the red line."
