One of my favorite features in ASP.Net is how pages are rendered in other browsers. It seems that ASP.Net thinks that there are two kinds of browsers in the world: Internet Explorer and the “down level” browsers. You can get a great looking page in IE, but when you view the page in FireFox (or Opera, or Safari, etc) it looks strange. ASP.Net 1.x treats down level browsers different and strips out the formatting code that really wanted to use. It uses a BrowserCaps section in the web.config and machine.config to identify the browsers and from that definition, which features will be used to render the page. And that BrowserCaps definition is heavily weighted to IE, most other browsers get plain HTML.
slingfive.com has updated versions of the BrowserCaps section to correctly identify most of the other browsers and the features that they support. Your pages will look better in FireFox and Opera and should load faster too.