Test, Test, Test that Presentation…
Presentation usually isn’t an issue for blind Internet users, because that issue is more about structure and content except when your stylesheet link crashes a browser. When that happens, a blind user’s screen reader cannot read your page. So, although you might be concerned with how your Website design appears to those users who can override your design with other stylesheets and even more so with those viewers who can see your design, the mismanagement of the link between structure and presentation may affect other users as well.
HTML/XHTML and CSS validation are the first steps to assure that your Website design won’t break because of sloppy or mismanaged code. And, you might repeat these tests over and over as you adjust that code. Other tests – other than those which reside on Opera’s User Mode applications – can help you visualize how others might view your site.
For example: My computer works with a Win32 platform with Windows XP, and Opera 8.51, IE (Internet Explorer) 6.0, and Mozilla Firefox 1.5.0.1 browsers also reside on this machine. I utilize these three browsers when I build sites, because each one translates my efforts differently. Firefox and Opera demand more precision. If I mess up, the site might not show in either browser. I like how those two browsers read my code accurately as well; however, I also like how IE manipulates my code, because I’ve learned a lot about how to manipulate IE through this effort.