Hmm, i'd like to disagree a bit with you two. IMO, one big part of CSS is to separate style from content and let graphic designers do their thing without interfering with the use of the website. For instance, i can read these forums comfortably no matter what font size is specified in the CSS, because with Opera i turn off CSS with the click of a button and i get to read the text not only at my preferred size (all of p1r's text appear the same size to me), but also in my preferred font which is not one of the standard ones. But if i go to an artist's website, i turn CSS on because there, the design is more important than the text.
Once you style a web page, there's no way to keep everyone happy. Style the page for the majority of the users and let the rest read the page with styling off. Easy.
There are TWO parts to "Web design": graphic design and content / intraction. CSS is ALL about graphic design. HTML is the part that does the content and interaction. If you're bundling both together, you may want to rethink your approach.
Yeah, except it's too bad there's no straightforward way to specify in CSS that "this page has 3 columns, put element foo in column 1, element bar in column 2, ..." Instead we have to conjure a mess of divs, floats, margins and widths to create "columns", that may or may not work in your particular browser. Funny how people miss the basic shortcomings of CSS for all the badly implemented websites out there.
Usability maybe, but typographic/graphic design has nothing to do with accessibility. If someone can't use a website with the author's styling, they should simply turn it off.
This is all you need to do: develop your page without CSS and with images off. Congrats, you now have an accessible website. Now add CSS, go crazy, who cares if it's not totally accessible, just make sure it's still usable. Done.
If you still want your styled website to be accessible, use standard class names and publish these on your website so that users can override the parts they don't like through their local CSS file.