If you are a web designer or document author interested in sophisticated page styling, improved accessibility, and saving time and effort, this book is for you. All you really need before starting the book is a decent knowledge of HTML 4.0. The better you know HTML, of course, the better prepared you'll be. You will need to know very little else in order to follow this book.
This second edition of the book covers CSS2 and CSS2.1, the latter of which is in many ways a clarification of the first. While some CSS3 modules have reached Candidate Recommendation status as of this writing, I have chosen not to cover them in this edition. This was done in part because the book seemed long enough without them, but also because implementation of these modules is still incomplete. I feel it's important to keep the book focused on currently supported and well-understood levels of CSS, and leave any future capabilities for future editions.
Remember one thing about web standards and books: the former are continually evolving, while the latter are frozen in time (until the next edition comes out, anyway). In the case of (X)HTML and CSS, many changes are afoot even as these words are being written. Despite this, it is my hope that this second edition will stay relevant over a period of several years, as did the first edition.
In order to keep the text relevant, as well as to save space, I cut CSS support information from this edition. Such information is much better published online, where it can be corrected and updated whenever there are changes in browser CSS support. Committing such information to paper, while useful in the first edition, no longer makes a great deal of sense. This is doubly true because CSS support has advanced so far in the last few years that whatever bugs remain are difficult to express in a simple chart. For example, as of this writing there is a bug in Safari in which applying text-transform through a :first-letter rule triggers some very strange behavior. There is, practically speaking, no good way to represent this in a chart, even a three-dimensional array. Furthermore, the bug is expected to be fixed in the very near future, and in fact may already have been fixed by the time this book is on shelves.
Therefore, rather than doom large portions of the book to obsolescence the moment they are published, I instead dropped the information. Doing so actually enabled me to keep the book from growing too much while adding a great deal more information. The support information I did preserve was that relating to bugs and limitations in the Internet Explorer line, which has ceased development.