UBB.threads PHP Forum Software Community Forums UBB.threads Installation and Upgrade Support Style issue with Firefox

I think this is a webserver configuration error on how .css files are being served. In Firefox, I get the following message in the Error Console:

Error: The stylesheet http://vsplanet.com/ubbthreads/styles/ubbthreads-dark_1194890335.css was not loaded because its MIME type, "text/plain", is not "text/css".