Hugh McCracken, Lecturer, Information Systems and Technology, School of Information Science and Humanities, The Open Polytechnic of New Zealand, Private Bag 31914, Lower Hutt, New Zealand. Email: mcchug@topnz.ac.nz.
Accessibility, Cascading style sheets, CSS, future compatability, support, eXtensible hypertext markup language, XHTML.
A case study website: http://www.baldwin-steam.org.nz/ uses a combination of cascading style sheets (CSS) and presentation markup to define styles and layout of web documents. CSS provides the mechanism for complete removal of presentational markup from document structure. It would provide consistent styles throughout the site and ease site maintenance and development. CSS had been used with caution, as older browser versions had either not supported or only provided partial support for the CSS specification. Browser support for CSS has improved since first release, with latest browser versions implementing the CSS1 specification. An evaluation of current browser statistics shows that browser types and versions that do not support CSS are a minor proportion of those in use. User agents other than browsers are also used to access web documents.
CSS in conjunction with extensible hypertext markup language (XHTML) improves web document accessibility to all users, irrespective of user agent, environmental constraint or disability. The World Wide Web Consortium (W3C) CSS specification refers authors to the W3C Web Content Accessibility Guidelines (WCAG), and in turn to the Access Board Section 508 guidelines for important accessibility recommendations. The web documents were revised, removing presentational markup from the document structure. A variety of techniques were used to check for accessibility, including validation tools, manual checks with a different user agents and alternative style sheets to simulate a common colour-blindness condition.
Analysis of the population of users who might access a web document shows that the proportion of those with disabilities far outweighs the proportion with older versions of browsers. Application of the W3C WCAG recommendations to a web document will result in enhanced accessibility for the majority of users, whilst still supporting the use of older browsers and ensuring future compatibility with user agents that have not yet been released.
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