CSS Standards and Versions

Like just about every aspect of information and computer technology, CSS — and web design itself — is in a constant state of flux, ever-changing and constantly evolving. Currently there are three versions of CSS — yep, you guessed it: CSS1, CSS2, and CSS3. Oh yeah, and the currently “Recommended” version of CSS2, CSS 2 revision 1, or CSS 2.1, which fixes some bugs and removes some poorly supported features of the original CSS2. (If you're wondering about how and why a markup or style sheet language becomes Recommended, it's explained in Chapter 1.)

The process for developing and deploying markup and style sheet languages is at best fuzzy and can be highly confusing. Often the new version of a language gets put to work piecemeal; the design community and the makers of web browsers start implementing parts of the new version almost immediately after the W3C announces that they've begun working on it. Take HTML5, for example. It's still a ways away from becoming a candidate for Recommendation, but parts of it are already widely used. Most of the popular web browsers, such as Internet Explorer, Firefox, Apple's Safari, and Google's Chrome — along with many mobile device browsers — support much of HTML5. The same is true of CSS. Although version 2.1 is the Recommendation, CSS3 is already ....