Is the "css" folder an actual folder right on the webroot? Or do you have a ColdFusion mapping created for "css"?
Normally, the web server (IIS, Apache, etc.) will serve the static resources like .css and .js files, as long as they are web-accessible. ColdFusion doesn't even need to be involved. However, if the files are not web-accessible (like in a folder above the web root or elsewhere), and ColdFusion is able to see them using a mapping, then you need to create is a virtual directory on your web server to point to the same place as your ColdFusion mapping. Then your web server can serve up those resources.
HTH,
-Carl V.
