Cascading Style Sheets was developed by a World Wide Web Consortium team headed by Bert Bos and Håkon Lie. The intent of the project was to create a styling language that could be integrated with HTML and XHTML to complement its structuring capabilities with styling rules.
CSS has been in the planning stages as long as HTML. But when HTML first came out, the technology did not exist to make use of CSS. CSS was not implemented as a standard until after computer monitors allowed for full multimedia display, instead of just spiffied up text.
By the time CSS was released as a standard the browser companies had altered HTML to include many styling commands in order to make HTML documents more attractive. This means that although the idea for CSS has been around as long as HTML, it is playing catch up with HTML technology. It is not so much as new set of standards standard as a pulling back in line of markup languages with the original conception of the standards.
Variations of CSS
The first version of CSS, CSS1, was released in 1996 and includes basic styling functions such as font, color, and background images. Most current browsers fully support CSS1.
CSS2 came out in 1998, and it added some high end features to CSS. CSS2 allows for positioning of elements on the page for page layout, provides support for downloadable fonts, and allows pages to be formatted for printing.
By providing a means to avoid the use of tables in page layout, and by allowing pages to be formatted entirely differently for paginated (printed) layout versus continuous (on-screen) layout, CSS2 has become a language that has gone beyond anything one could ever do with HTML.
Currently, no one fully supports CSS2, although Opera 6 and Netscape 6 both have almost total support. Exploror 6 has extensive support. Netscape 4.x has almost no CSS2 support.
A browser or other user agent needs to be as close as possible to fully CSS2 compliant in order to make use of CSS with XML.
CSS3 is still in development, but will add support for additional presentation media to the mix, such as aural (audio) styling. CSS3 will also involve a restructuring of CSS into modules that support different styling elements. This will not affect older style sheets, it will merely provide a better way of structuring new ones.
Most of what is going on in the development of CSS3 will not affect the way in which you use CSS to format documents for display on a computer screen.
Besides, currently the css profile for mobile devices, printers, and television sets.
The first CSS specification to become an official W3C Recommendation is CSS level 1, published in December 1996.Among its capabilities are support for:
- Font properties such as typeface and emphasis
- Color of text, backgrounds, and other elements
- Text attributes such as spacing between words, letters, and lines of text
- Alignment of text, images, tables and other elements
- Margin, border, padding, and positioning for most elements
- Unique identification and generic classification of groups of attributes
The W3C no longer maintains the CSS1 Recommendation.
CSS level 2 specification was developed by the W3C and published as a Recommendation in May 1998. A superset of CSS1, CSS2 includes a number of new capabilities like absolute, relative, and fixed positioning of elements and z-index, the concept of media types, support for aural style sheets and bidirectional text, and new font properties such as shadows. The W3C no longer maintains the CSS2 Recommendation.
CSS level 2 revision 1 or CSS 2.1 fixes errors in CSS2, removes poorly-supported or not fully interoperable features and adds already-implemented browser extensions to the specification. In order to comply with the W3C Process for standardizing technical specifications, CSS 2.1 goes back and forth between Working Draft status and Candidate Recommendation status. CSS 2.1 first became a Candidate Recommendation, but it was reverted to a Working Draft on June 13, 2005 for further review. It was returned to Candidate Recommendation status on 19 July 2007 and was updated twice in 2009. However, since changes and clarifications were made to the prose it went back to Last Call Working Draft on 7 December 2010.
Instead of defining all features in a single, large specification like CSS2, CSS3 is divided into several separate documents called “modules”. Each module adds new capability or extends features defined in CSS2, over preserving backward compatibility. Work on CSS level 3 started around the time of publication of the original CSS2 Recommendation. The earliest CSS3 drafts were published in June 1999.
Due to the modularization, different modules have different stability and are in different status.As of March 2011, there are over 40 CSS modules published from the CSS Working Group.Some modules such as Selectors, Namespaces, Color, Media Queries are considered stable and are in either Candidate Recommendation or Proposed Recommendation status.Once CSS 2.1 is finalized and published as Recommendation, they are likely to go to Recommendation as well.