probably...
haven't tried it but the browser may have an issue with the .php extension. If that's a problem you can simply add the extension to your httpd.conf file or in .htaccess
You should see somthing similiar to this in your httpd.conf file or if you don't have access you can create a .htaccess file in the directory root and insert something similiar to this:
AddType application/x-httpd-php .php3 .phtml .php .php4 .html .htm
The important part is you add .css to the list. This will allow php to parse .css files (and the browser shoudn't know the difference.)