Cascading Style Sheets

In spite of what people might tell you, HTML is a markup language created to define Web page structure not presentation. However, shortly after the introduction of graphical Web browsers, determined individuals realized they could force presentation features using certain HTML coding elements and attributes. Compounding the problem further, Web browsers would process the HTML because the browser is concerned about the validity of the element s existence, not the validity of the element s presentation definition.

Soon site designers began implementing tables to position text and graphics on a page. Then HTML headers were coded to achieve a particular font style with no regard for HTML s defined hierarchy (H1, H2, H3, and so on). In other cases, elements were used to convey structure that could only be understood in a visual context (for example, tabular data was presented using the PRE element).

Each of these examples complicates the rendering and comprehension of a Web page for a person with a visual disability. Tables, for example, by their very nature (columnar) are difficult for a blind person who uses a screen reader to comprehend because screen readers read lines of information left-to-right, line by line. You can imagine how difficult it is for a person who relies on a voice-based user agent or screen reader to interpret that a Web site s table isn t a table of tabular information, but rather a means for laying out the presentation of that page. Navigation is often a nightmare.

True, recent advances...