Well, I fixed my zindexing problem in http://stores.tiefert.com/books/index.html , but it turns out that opera apparently doesn't like you to use % values for vertical positioning. I want to have the menu boxes scattered around in the main part of the page, and I want the design to be as liquid as possible, and I don't want to fix the sizes of the menu boxes because I don't want the page to be uglified by scroll bars or chopped off text in the boxes.

So positioning is done with, for example:
.science { 
	position: absolute; 
	left: 30%;
	top: 22%; 
	background-color: #fff7ea; 
The css positioning works OK enough in Mozilla and IE (the horizontal positioning is liquid, but the vertical positioning isn't particularly). Horizontal positioning is also OK in Opera

But vertical positioning is messed up in Opera -- all the menu boxes are at the top of their containing div! Any solutions? Or is this just another bug? It doesn't matter whether Opera identifies itself as Opera, Mozilla, or IE.