layer at (0,0) size 800x600
  RenderCanvas at (0,0) size 800x600
layer at (0,0) size 800x50
  RenderBlock {HTML} at (0,0) size 800x50
    RenderBody {BODY} at (8,16) size 784x18
      RenderBlock {P} at (0,0) size 784x18 [bgcolor=#00FF00]
        RenderText {TEXT} at (0,0) size 268x18
          text run at (0,0) width 268: "This line should have a green background."
