Variations of css1, css2 and css3

The CSS specifications are maintained by the World Wide Web Consortium (W3C). Internet media type (MIME type) text/css is registered for use with CSS by RFC 2318 (March 1998).

CSS 1

The first CSS specification to become an official W3C Recommendation is CSS level 1, published in December 1996.^[16] 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.^[17]

CSS 2

CSS level 2 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 maintains the CSS2 Recommendation.^[18]
CSS level 2 revision 1 or CSS 2.1 fixes errors in CSS2, removes poorly-supported features and adds already-implemented browser extensions to the specification. While it was a Candidate Recommendation for several months, on June 15, 2005 it was reverted to a working draft for further review.^[19] It was returned to Candidate Recommendation status on 19 July 2007.

CSS 3

CSS level 3 has been under development since December 15, 2005.^[20][21] The W3C maintains a CSS3 progress report. CSS3 is modularized and consists of several separate recommendations. The W3C CSS3 Roadmap provides a summary and introduction.^[22]