CSS Master: Organized, Efficient, Powerful-CSS Done Right – Free eBook
You’ll come away from this book with a better sense of how CSS works and how to write it well.
This book is for intermediate-level CSS developers, as it assumes a fair amount of experience with HTML and CSS. No time is spent covering the basics of CSS syntax.
Disclaimer: This free eBook is a part of third party affiliate program and provided by great folks at sitepoint.