layer at (0,0) size 800x600
  LayoutView at (0,0) size 800x600
layer at (0,0) size 800x600
  LayoutBlockFlow {HTML} at (0,0) size 800x600
    LayoutBlockFlow {BODY} at (8,8) size 784x584
      LayoutText {#text} at (20,1) size 470x19
        text run at (20,1) width 470: " This checkbox should look 50% transparent and should be in the mixed state."
      LayoutText {#text} at (0,0) size 0x0
layer at (12,11) size 13x13 transparent
  LayoutBlockFlow {INPUT} at (4,3) size 13x13