layer at (0,0) size 800x600
  RenderCanvas at (0,0) size 800x600
layer at (0,0) size 800x45
  RenderBlock {HTML} at (0,0) size 800x45 [bgcolor=#00FF00]
    RenderBody {BODY} at (8,14) size 784x17 [bgcolor=#000000]
      RenderBlock {P} at (0,0) size 784x17
        RenderText {TEXT} at (0,0) size 343x17
          text run at (0,0) width 343: "The background of the document should be green"
