My settings in Firefox 3.0.1 was already like that. It looks OK on a first page here but not on a second. The web server sends the wrong content-type. I use curl in Linux to print the header:
$ curl -D header 192.168.0.223/toplevel.css 2&>1 /dev/null ; cat header
HTTP/1.1 200 OK
Server: EMG/1.1.0
Cache-control: no-cache
HTTP Server By Eric Gregori Version 1.1.0
Content-type: text/html
Content-length: 9640
On another web server (Apache) the same file is sent with content-type text/css. I think this is why it doesn't apply the style sheet. The content-type is determined by emg_static_ffs.exe.