There is a book about Cascading Style Sheets that I find helpful and unique. It is Dan Cederholm's Web Standards Solutions and the reason it is so helpful is that it focuses on what markup to use as much as on how to get your style sheets right. Learning to use style sheets is a bit tricky and getting the markup right is one part of the trick. So I highly recommend this book if you're just getting into style sheets or if you've tried before without success.

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