layer at (0,0) size 800x600
  RenderCanvas at (0,0) size 800x600
layer at (0,0) size 800x51
  RenderBlock {HTML} at (0,0) size 800x51
    RenderBody {BODY} at (8,8) size 784x30
      RenderBlock {PRE} at (0,0) size 784x30
        RenderText {TEXT} at (0,15) size 104x15
          text run at (0,15) width 104: "Some pre text"