Cascading Style Sheets Resources

CSS Test Suite
"The CSS1 Test Suite is provided as a way for vendors and page authors to test their browser's conformance to the CSS1 specification." (Guess what? Both NS and IE fail.)

W3C CSS Validation Service
Validate your cascading style sheet by URL, text area, or file upload. http://jigsaw.w3.org/css-validator/

Style Sheets Activity page (updated 6/22) -- IMPORTANT TO READ!
Much like the Markup Activity page, this page highlights the advantages of CSS2 over CSS1, acknowledges browser implementation problems with CSS1, discusses how XSL will be used in conjunction with XML to produce HTML and CSS, and much more.

eXtensible Style Language (XSL)
eXtensible Style Language (XSL) is a user-extensible and primarily declarative mechanism for adding style (e.g. fonts, colors, spacing) to XML documents.

W3C's List of CSS Resources	Cascading Style Sheets (CSS) is a simple mechanism for adding style (e.g. fonts, colors, spacing) to Web documents. For background information on style sheets, see the Web style sheets resource page. Discussions about CSS are carried out on the www-style@w3.org mailing list and on comp.infosystems.www.authoring.stylesheets.
Cascading Style Sheets - Designing for the Web	If I were to recommend just one book to an enquiring web developer - this would be it. Superbly well-written by the experts, it's highly readable and informative.
Web Style Sheets	Style sheets describe how documents are presented on screens, in print, or perhaps how they are pronounced. Style sheets are soon coming to a browser near you, and this page and its links will tell you all there is to know about style sheets. By attaching style sheets to structured documents on the Web (e.g. HTML), authors and readers can influence the presentation of documents without sacrificing device-independence or adding new HTML tags.
W3C Cascading Style Sheets page.	This document specifies level 1 of the Cascading Style Sheet mechanism (CSS1). CSS1 is a simple style sheet mechanism that allows authors and readers to attach style (e.g. fonts, colors and spacing) to HTML documents. The CSS1 language is human readable and writable, and expresses style in common desktop publishing terminology. One of the fundamental features of CSS is that style sheets cascade; authors can attach a preferred style sheet, while the reader may have a personal style sheet to adjust for human or technological handicaps. The rules for resolving conflicts between different style sheets are defined in this specification.
HTML Card by VisiBone	HTML and CSS quick reference card in a rich, lucid, dense 4 pages. Examples, tag list, style property list, special characters, browser compatibility color theme, bugs and clashes with details online, SSI, URLs, XHTML. Wall charts too.
JavaScript-Based Style Sheets; "JSSS" Initial Proposal.	This document specifies the JavaScript-Based Style Sheet mechanism (JSSS). JSSS is a powerful style sheet mechanism to attach styles to HTML documents using the existing property-based language JavaScript. Specifying styles through the JavaScript programming language allows for the use of functions and assigned values to make the expression of style easier for the creator. With the reflection of CSS1 properties into scripting, JSSS facilitates developers in taking full advantage of style sheets.
Cascading Style Sheets Guide	Style Sheets, while not meant to control layout, are a simple yet powerful method of allowing attachment of rendering information to HTML documents. The language syntax for specifying Style Sheet information is quite different than HTML, so significant explanation will be required. To make it worse, the specification from W3 for Style Sheets is still changing significantly, even while many browser vendors rush to support it. Style sheets authored today may need revision in future months until the specification settles down.