CSS PATTERNS AND ADVANCED TECHNIQUES
As you saw in the earlier chapters of this book, much of what CSS is capable of depends heavily on organized and well-formed HTML or XML that's largely self-describing by working in concert with the semantic structure of the markup. Starting out this way, the markup itself functions as a sort of application programming interface (API) for other purposes. One common purpose for such semantic markup is to ease transformations from one format to another or extract data from it, as microformats and RDFa can do today.
In much the same way, CSS itself can benefit from being equally “self-describing.” Writing CSS that is not merely readable but meaningful creates additional patterns and improves the reusability ...