The primary challenge of web accessibility is to make the content of web pages readily available to as many users as possible. If accessibility was the only objective, the challenge is relatively small, as we can design very plain, simple and straightforward pages. The HTML version of this document, for example, is very friendly to assistive technologies.
The challenge is that we also want web pages to be attractive to the “average” users. HTML and CSS (cascading stylesheet) offer many features that can make a web page look very pretty. However, some of these features can also make it difficult for assistive technologies.
As a web designer, the challenge is to create solutions that work for users who do not need assistive technologies, as well as users who need assistive technologies.