Why does Internet Explorer not parse my CSS?

In my previous question (asked before I registered), I asked why my ACM chapter's site doesn't get all the way through IE's CSS parser. Got an answer, but after turning on Drupal's CSS caching which merges all CSS into one file, absolutely no CSS is handled. What gives? The CSS validator says there's a few bugs but none of them look like they'd be absolutely fatal.开发者_JS百科

Running your CSS through a validator shows you have heaps of errors, you might want to fix those.

http://jigsaw.w3.org/css-validator/validator?uri=http%3A%2F%2Facm.cs.uakron.edu%2Fsites%2Fdefault%2Ffiles%2Fcss%2Fcss_753a2c990c630e98f7da739ed5ca7c79.css