Ten years ago, on 17 December 1996, W3C published the first standard for style on the Web: Cascading Style Sheets (CSS), level 1. CSS Web designers have since enjoyed fine-grain control of page appearance (fonts, colors, layout, margins, etc.) and easier page design and maintenance. CSS can also help make pages more adaptable to more users, including users with mobile devices and some users with disabilities.
"The design community has confirmed that using CSS, and separating markup from presentation, promotes beauty while making it easier and less expensive to build sites, " said Bert Bos, W3C Style Activity Lead and one of the original co-authors of the specification that became CSS level 1, published on 17 December 1996.
In addition, thanks to the efforts of users, developers, and translators, W3C has released a new version of the CSS validator in time for CSS10.
CSS Separates Markup from Presentation, Benefitting Designers and Users Alike
CSS success derives from its numerous benefits to designers. The first benefit is the rich feature set. Using a simple declarative style, designers can set positioning, margins and alignment, layering, colors, text styling, list numbering, and much more. Furthermore, writing direction, font styles, and other conventions differ from one written language to another. CSS supports an increasing number of different typographic traditions and has made significant progress toward being able to display multilingual documents.
The second benefit is reuse. Style sheets can be shared by multiple pages, making it easy to update an entire site by changing a single line of CSS. Because style sheets can be cached, this can mean improved performance as well.
CSS promotes accessibility in a number of ways, without compromising design. Separating markup from style enables accessibility agents to convey information according to the needs of users with disabilities. The CSS design strikes a good balance between author and user needs, enabling users to make use of more pages. Style sheets also reduce dependency on using HTML tables for layout, which can be a barrier to some users with disabilities using assistive technologies such as screen readers.
A related CSS benefit is easier cross-media publishing; the same document may be viewed with different devices (from large color monitors to mobile phones to printers) simply by applying the appropriate style sheet. Software can choose the most appropriate style sheet automatically (as suggested by the style sheet author), and allow the user to choose from among available style sheets to meet that individual's needs.
CSS is commonly used to style HTML and can also be used with XML documents as a complement to W3C's XSL.
CSS3 Targets Multimedia, Multimodal
CSS has various levels and profiles. In general, desktop browsers implement level 1, 2 or 3. Other programs implement the appropriate profile for their platform, whether mobile phone, PDA, television, printer, speech synthesizer, or other device.
CSS level 1 defines properties for fonts, margins, colors, and other tools for style that are common to nearly all profiles of CSS. An early example of CSS use is the original CSS gallery (written when Microsoft's Internet Explorer 3 added CSS support). W3C has compiled more CSS history as part of this celebration.
CSS level 2 revision 1 (CSS 2.1) includes all of CSS level 1 and adds absolutely positioned elements, automatic numbering, page breaks, right to left text and other features.
CSS level 3 (CSS3), still in development, promises more power features at the same time it will make CSS easier to implement and use. CSS3 includes all of level 2 and adds new selectors, rich hypertext, more powerful borders and backgrounds, vertical text, user interaction (e.g., styling of XForms), speech, rendering on multimedia devices, and more; see the CSS Working Group charter for details.