wolf73,
You might be mis-understanding. You use HTML to build websites. Period.
CSS is simply a way of telling the HTML on the page how it should look. It is not a substitute for HTML.
To really understand how using CSS to lay out your pages is different from using, say, HTML tables, you need to use a browser that lets you turn off style-sheets. I recommend downloading Firefox, and installing the "Web Developer Toolbar" from Chris Pederick. Once installed, you can turn off all styles to see a page "au naturel" (i.e. just as plain HTML).
Sites whose layout is achieved with tables generally look quite hideous with styles turned off (this one included). Sites whose layout is achieved via CSS generally look a lot more understandable, and easier to follow the flow of the content. Take this recent site we built:
It's a good example of what I'm talking about. If you turn styles off, you can still read the content in quite an obvious way. Nothing is hard to understand. Turn styles off on this site, and you'll be struggling to work out what is where.
While humans might be able to understand sites built using table-based layout with no styles, screen readers can often have a much harder job.
Hope this helps,
Dan
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