Obviously, the best thing to do is detect the browser and serve the approriate style sheet, and the safest way to that is on the server-side using PHP, ASP, XSSI, or something similar. But, if that's not an option, it can be also be done on the client-side using JavaScript. A third option is more problematic, but can be successful: exploit a known bug in Netscape 4.x. Find out more.