Using Drupal variables in CSS? I'm using CSS to implement a banner image in my theme:

#banner {
    background: url("../images/banner.jpg") no-repeat fixed 
}


Site users would like to be able to change the image within Drupal. I'm thinking of adding a file upload field to the Site Information admin form, and insisting that only a file with the same name (banner.jpg) is uploaded.

I wonder if it would be possible to use a Drupal variable in my CSS instead? Then a file name change wouldn't matter. I've used CSS in .php files before (setting the content type back to CSS in the header), but never tried this in a Drupal theme.
You can apply css styles from php. Use the drupal_add_css() function 

&lt;?php
drupal_add_css('#banner { background: url("../images/banner.jpg") no-repeat fixed }',$option['type'] = 'inline');
?&gt;