Apart from writing a ton of articles for his website this year, Ahmad has also written a book on Debugging CSS:
An ebook with lots of tips and techniques on how to debug CSS the right way with easy and studied methods.
It’s a very practical book that should get you help solve any potential CSS issues you might run into.
Side note: I’m proud to have been asked to review this book while it was still in the making, and am glad I was of help to Ahmad. Great job you did there!