The file must end with a css extension. Scripting comes in two varieties as I have learned to use it. The first is Javascripting, which I know a little about, and the second is CGI scripting, which I know nothing about. Javascript does much of the neat things you see on pages, but CGI scripting does much of the server work like taking credit card numbers, and stuff like that. Java Script is a scripting language that comes from Sun Microsystems, and Microsoft and Netscape have each altered it a bit to suit their browser and accept its commands in different ways.
Some scripts work in only one browser, while others work in both.
If you did your page in Front Page from Microsoft, look at it in Netscape. Yes, it is crazy and frustrating. No, Microsoft doesn't care. Yes, it will require rewriting your scripts to make sure they work in both browsers. Get a hit counter from someone and have it collect stats for a month or two, or, check to see if your server collects stats.