When I apply a buffer or rectangle to my labels they show through the overlying layers. Is there any way to avoid this, i.e. arrange the label so it lies underneath the layers above? I'm assuming the labels themselves take priority and lie on top of any layers above (I've tried playing with the various priority settings). The yellow layer below has some transparency. I want to include a space around the label so it blocks the underlying contour line, but I don't want the buffer or rectangle showing through the yellow layer.