I really liked David McFarland’s CSS: The Missing Manual when it came out in 2009, and I’ve recommended it for several years. However, he’s got a new version – CSS3: The Missing Manual that came out in late January 2014. It’s an improvement over his first volume and I’d recommend you upgrade if you’re writing, modifying, or maintaining Cascading Style Sheet or if you just want to learn more about CSS.
Fortunately for me, CSS3: The Missing Manual is available through iTunes for Apple users, Naturally, it’s also available on Safari and Kindle formats. As an Apple user, I opted for the iBook format for my iPad Air. Unfortunately, it’s $27.99 as an iBook compared to $15.49 on Kindle, and that almost makes me opt to use the Kindle App.