including HTML in the CSS document. So here's a couple of possible answers:
1) HTML may not be included in the CSS definitions page where you define your CSS classes. Classes/styles modify HTML tags, not the other way around.
2) The ID tag doesn't reference anything, it *is* the reference to the tag it is embedded in. It may be used to modify a tags CSS properties, but only really via javascript like so:
document.getElementById('someId').style.display='none';
3) If you want to make your code easier to maintain via centralization (and I whole heartedly approve of that!) you should separate all your menu code, HTML and all into another file and do an include of the menu into each other page where you would normally have had the menu HTML on that page. Here's a php example:
<TR><TD>Here's my menu</TD></TR>
<TR><TD><?php include("mymenu.php"); ?></TD></TR>
with mymenu.php holding the HTML that is your menu. There are many ways to do includes, and it all depends on the scripting language you are using. Heck, you can even do includes without a scripting language (
http://www.15seconds.com/faq/IIS%203.0/346.htm">server side includes-IIS,
http://httpd.apache.org/docs/1.3/howto/ssi.html">server side includes-Apache).
4) It just gets more complicated from there! :P Seriously though, if you have any questions just send a message to my DU inbox. I'm just doing DB migrations now, and that's boring as hell, so I'd be glad to answer any questions.