You can have multiple stylesheets, as needed.
ie. from my university's site:
Code:
<link rel="stylesheet" href="http://communications.uwo.ca/standard1c.css" type="text/css" media="all" />
<link rel="stylesheet" href="http://communications.uwo.ca/standard2c.css" type="text/css" media="all" />
<link rel="stylesheet" href="http://communications.uwo.ca/style3c.css" type="text/css" />
<link rel="stylesheet" href="http://communications.uwo.ca/print.css" type="text/css" media="print" />
I think the hierarchy is such that the first stylesheet overrides the second, and so on.