Found this today looking for a was to find redundancies and unused CSS rules in my code. I have adopted a technique they call divide and conquer. Split all my CSS rules up into different categories and separate them from my pages. I use import in the head of my pages.
Scroll down a bit to the "Cascading Style Sheet Tools
" section and you'll find stuff for validation, cleaning, optimizing, file reduction very handy resources.
You'll have to sort out what is useful and not, also note that some links are dead. :-(