layer at (0,0) size 800x600
  LayoutView at (0,0) size 800x600
layer at (0,0) size 800x50
  LayoutBlockFlow {HTML} at (0,0) size 800x50
    LayoutBlockFlow {BODY} at (8,16) size 784x18
      LayoutBlockFlow {P} at (0,0) size 784x18 [bgcolor=#00FF00]
        LayoutText {#text} at (0,0) size 272x17
          text run at (0,0) width 272: "This line should have a green background."