This is the first div. It uses position: relative and has set a z-index.
This is the second div. It uses position: relative only, no z-index is set.
This is the third div. It uses float: left, and uses position: relative. No z-index is set.
This is the fourth div. Neither position: relative, float: left or z-index is used. It does however use position: static.
This is the fifth div. Nothing is set about this, apart from the same background-properties as set for every div. You should, if you are using Opera 7, build 2577, that the background of the second div is different from the rest, even if they use the same image. This is, obviously, a bug inO7 related to position: relative. If you are using Mozilla, you will notice that the third div, that has set a float: left, but no z-index renders with the wrong opacity.