Web page design can miss the mark through bad navigation, poor maintenance, and bloated graphics.
Speed is the most basic example of accessibility.
Don't stop at fast graphics and a catchy domain name. Most people come to the web for information, so your web site must serve up menus full of information, easy to find, intuitive to navigate. Different versions of such browsers as Internet Explorer and Netscape are notoriously different in the way the see certain elements on web pages. Many people have their computer monitors set at 256 colors, so what looks great to your designer looks horrible to your client. You have to test for accessibility, again and again.