Check a few articles about CSS specificity and they will explain your issue. Smashing Magazine and CSS Tricks had some good introductory articles about this subject some time ago, but there are plenty others around.
On a related note, long chains like .varLinks div li a:hover should be completely unnecessary and only serve to reduce rendering performance (albeit very marginally) and make your CSS harder to maintain. Check out CSS combinators, which relate to specificity as well, actually.
Hope this helps you.