Multiple Style sheets (or disabling a sheet)

Is there any way to use one style sheet for part of a page and another for the rest?

Specifically I have an include (SSI) for a header that I want to use a different CSS than for the rest of the document.

It would be nice to be able to "disable" a style sheet in other circumstances too. I'm guessing the answer is "no" since my google searches have not turned up anything.

Elfboy,

if you put the contents of your header in a <div id="header"> and the rest of your page in a <div id="content"> you can write your CSS like this:

#header {background:black;color:white;}
#header h1 {}
#header p {}
#header a:link {}
etc.

and for the contents:

#content {background:white;color:black;}
#content p {}
#content p span {}
#content a:link {}
and so on.

You can put the CSS in one stylesheet (better) or use two @import statements or two links to include them.

Disabling a stylesheet is possible with a little JavaScript.
http://www.quirksmode.org/js/cssdisable.html

Thanks SPAN!
I think the first part is just what I'm looking for. I'll also look at that javascript, but the others I've seen are "all or nothing".