Find CSS not applied rules

Question

I have a big CSS styles sheet, (about 6500 lines). Is there any way to determine which rules do NOT apply in a given page, (firefox plugin, a web util, or something) ?

Answer 1

In the FireFox add-on, Firebug, CSS rules which are overridden by other rules are crossed out.

Answer 2

Firefox, add extension Dust-Me Selectors. It does just that