do i need to output headers on parsed CSS files?

Hi all, I'm forcing my style sheets (.css) though the PHP parser, so that they can take advantage of some color variables and global config settings via include files, eg: body { background-color: #<?=$col['1']?>; } however, I've noticed that when viewing the CSS file in a browser now, it looks more like a HTML document int he browser (variable width fonts, no newlines, etc) rather than other css files (wich look like they have <pre> tags aroun them (newlines visible, fixed-width font, etc). So, my assumption is that pushing the .css file through PHP is putting the wrong header on the file (text/html) rather than text/css -- or perhaps something else -- my header knowledge is poor. Anyway, the pages and linked CSS files *work* but do not validate any more, witha warning "You can't import an HTML document". What/how should I force the correct headers on these PHP-parsed CSS files? TIA Justin French