Xhtml. Firefox Add-ons. Dave Raggett's Introduction to CSS. Dave Raggett, 8th April 2002.
This is a short guide to styling your Web pages. It will show you how to use W3C's Cascading Style Sheets language (CSS) as well as alternatives using HTML itself. The route will steer you clear of most of the problems caused by differences between different brands and versions of browsers. For style sheets to work, it is important that your markup be free of errors. A convenient way to automatically fix markup errors is to use the HTML Tidy utility.