Although it sounds like a cliché, "CSS Mastery" is an excellent book, from the first to the last page. Most of book is written by Andy Budd, with Cameron Moll and Simon Collison contributing with final two chapters.
As easy as it is to find lot of content on Internet that would educate user what can be done with CSS, there's something special to have a book to articulate concepts from beginning to end providing a consistent narrative of the thought and methodology behind some technique's implementation. That is exactly what this book is providing.
Covering everything from the basics of marking up documents properly by using clean, semantic and valid (X)HTML to the advanced CSS tips and tricks. The foundations of CSS are explained as well along with ways to resolve browser bugs on which web designer can run into. Authors will teach you how to style forms and data tables, how to use lists to able creating visually appealing content.
PDF file with errata is available for download from the book's accompanying website where also sample chapter, the table of contents and all the code included in the book can be found.
For the couple of times at least during the read I was happy to realize "...how something works" or "...that's the way they done it" so whether you're new or experienced to CSS for sure you will also find this book useful.
Chapter 1 called "Setting the Foundations" addresses usage of meaningful markup, using classes Vs. ids, different versions of HTML and CSS, DOCTYPE among other things.
Chapter 2 called "Getting Your Styles to Hit the Target" discusses selectors, specificity, inheritance, style sheet planning and organizing, and style guides.
Chapter 3 called "Visual Formatting Model Overview" discusses the box model, differences with IE, positioning (relative/absolute/etc.) and floating.
Chapter 4 called "Using Backgrounds for Effect" discusses using images for list bullets, various rounded corner techniques (including border-radius), multiple background images, opacity (including RGBa), drop shadows and image replacement techniques.
Chapter 5 called "Styling Links" discusses all sorts of interesting ways to play up links, including creating CSS-only tooltips.
Chapter 6 called "Styling Lists and Creating Nav Bars" discusses all the various proven methods of creating CSS-styled navigation, but also includes excellent section about Flickr-style image maps creation.
Chapter 7 called "Styling Forms and Data Tables" discusses calendar styles and what markup can be used to make various layout methods for a simple form.
Chapter 8 called "Layout" discusses how to create fixed, elastic and liquid layouts, explaining the bonuses of each one.
Chapter 9 called "Bugs and Bug Fixing" discusses how to find and isolate bugs, reminding user to "...fix the problem, not the symptoms".
The final two chapters, tenth and eleven are the case studies for sample sites "Roma Italia" (by Cameron Moll) and "Climb the Mountains" (by Simon Collison). Both authors walk through their approach for site building and the implementation of various techniques. Both case studies serve as professional models for reader to be able to learn from and experiment with.
The book's only minor drawbacks should be addressed to some outdated data because of book release date, more color highlighting for code differentiation would be more than welcome and some content overlapping can be seen because three authors were part of this writing project. But all of these drawbacks are so minor comparing to all good things provided, although I wanted to mention them.
As verdict, I will quote Andy Budd who with sentence "...There are an increasing number of CSS resources around, yet you only have to look at a CSS mailing list to see the same questions popping up time and again." greatly summarized this book. The material contained here user can find somewhere else for sure, but if you're in a search for a handy collection of advanced techniques, you'll get that and much more from this book.
Probably this is the best book on the market for this subject, huge recommendation.