I personally write in Strict XHTML like Salathe. I have no problems with it in any browser - although I find if you're using MonoASP for a Linux Server Firefox merely loads up the code and displays it. Not very good for a fellow Open-Source Project...

I have never checked the Standards; I do not intend to. While my sites run on Internet Explorer, and at least load up on Firefox to show the use Internet Explorer Links and some Content I will live. If Firefox works with what works on Internet Explorer it would be a bonus - but a superfluous bonus. As I do not hold out any hope for Firefox being more than a fad, or gaining more than 8-9% of Browsers before the inherent Security problems in Netscape kick in and it can't keep up with the growing security of Internet Explorer.