Short ansewr, you can't. An "a" tag encompassing a "div" tag is invalid code. You can make it work like the menus work where the "a" tag is set to "display:block;" with padding and/or margins to make the block element act as a link rather than just the text.
This CSS Sprite Demo moves paragraph text off screen with text-indent: -9999em. But the anchor is set to display:block with added height & width to give it some girth. Span tags won't work for this.
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