“讨论:CSS 2.1”的版本间的差异

2007-08-24T16:25:58的版本

Cascading Style Sheets Level 2 Revision 1 (CSS 2.1) Specification

W3C Candidate Recommendation 19 July 2007

This version:

http://www.w3.org/TR/2007/CR-CSS21-20070719

Latest version:

http://www.w3.org/TR/CSS21

Previous version:

http://www.w3.org/TR/2006/WD-CSS21-20061106

Editors:

Bert Bos <bert @w3.org>

Tantek Çelik <tantek @cs.stanford.edu>

Ian Hickson <ian @hixie.ch>

Håkon Wium Lie <howcome @opera.com>

Please refer to the errata for this document.

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Copyright © 2006 W3C® (MIT, ERCIM, Keio), All Rights Reserved. W3C liability, trademark and document use rules apply.

Abstract

This specification defines Cascading Style Sheets, level 2 revision 1 (CSS 2.1). CSS 2.1 is a style sheet language that allows authors and users to attach style (e.g., fonts and spacing) to structured documents (e.g., HTML documents and XML applications). By separating the presentation style of documents from the content of documents, CSS 2.1 simplifies Web authoring and site maintenance.

CSS 2.1 builds on CSS2 [CSS2] which builds on CSS1 [CSS1]. It supports media-specific style sheets so that authors may tailor the presentation of their documents to visual browsers, aural devices, printers, braille devices, handheld devices, etc. It also supports content positioning, table layout, features for internationalization and some properties related to user interface.

CSS 2.1 corrects a few errors in CSS2 (the most important being a new definition of the height/width of absolutely positioned elements, more influence for HTML's "style" attribute and a new calculation of the 'clip' property), and adds a few highly requested features which have already been widely implemented. But most of all CSS 2.1 represents a "snapshot" of CSS usage: it consists of all CSS features that are implemented interoperably at the date of publication of the Recommendation.

CSS 2.1 is derived from and is intended to replace CSS2. Some parts of CSS2 are unchanged in CSS 2.1, some parts have been altered, and some parts removed. The removed portions may be used in a future CSS3 specification. Future specs should refer to CSS 2.1 (unless they need features from CSS2 which have been dropped in CSS 2.1, and then they should only reference CSS2 for those features, or preferably reference such feature(s) in the respective CSS3 Module that includes those feature(s)).