layer at (0,0) size 800x600
  RenderView at (0,0) size 800x600
layer at (0,0) size 800x600
  RenderBlock {HTML} at (0,0) size 800x600
    RenderBody {BODY} at (8,8) size 784x584
      RenderText {#text} at (16,0) size 500x18
        text run at (16,0) width 500: " This checkbox should look 50% transparent and should be in the mixed state."
      RenderText {#text} at (0,0) size 0x0
layer at (10,12) size 12x12
  RenderBlock {INPUT} at (2,4) size 12x12