Learning PHP, MySQL & JavaScript, 7th Edition

Chapter 18. Advanced CSS

The first implementation of CSS was drawn up in 1996 and released in 1999; it has been supported by all browser releases since 2001. The standard for this version (CSS1) was revised in 2008. In 1998, developers began drawing up the second specification (CSS2); its standard was completed in 2007 and revised in 2009, while development for the CSS3 specification commenced in 2001, with some new features proposed in 2009 and recommendations continuing to be made.

A CSS4 was proposed by the CSS working group, but the naming convention appears to have been dropped as this is not a major leap forward. Rather, it’s simply a development of one part of CSS—the selectors, and therefore mostly is referred to as Selectors Level 4 (see drafts.csswg.org).

Thankfully, though, the CSS working group publishes regular snapshots of the CSS modules that it considers stable, and you can see the 2023 snapshot here, which is the best place to gauge the current state of play in the world of CSS. You can learn more about how CSS3 has developed in practice as of 2023 (and also what’s coming) at the Chrome Developers Blog.

In this chapter, I’ll take you through the most important CSS3 features that have been adopted by the major browsers, many of which provide functionality that hitherto could be attained only with JavaScript.

I recommend using CSS to implement dynamic features where you can, instead of JavaScript. The features provided by CSS make document attributes part of the ...