I have some stylesheets from different sources in my web project. I want to harmonize them. Some styles I need from the one, some from the other. Is there a tool or method how
Have you tried this Firefox extension? Dust Me Selector http://www.brothercake.com/dustmeselectors/ It makes removing redundant styles much easier.
Otherwise, I'd probably pop all the styles into one file, trying to group together similar rules, and then use Dust-Me to remove the unused ones.