I stick with
XHTML and CSS. Dynamic stuff is done on the server side by PHP. If I do use Javascript, it is always in ways that only add functionality, but nothing is really affected if JS is disabled for some reason.
I tend to go the high compatibility route on website design. For instance, the fixed position property is great, but doesn't work on IE. If I do want to use that, I generally have it as an additional style sheet to the normal one. That way, I can give the user a link which, when clicked, tells the PHP to add that style sheet to the user's list (stored in a session) and add links in the header for future page requests.
Gosh... I'm tired. Hope that made sense.
