Conditional Comment

With this NON scrip technique, the browser info can be detected.
on MSDN: http://msdn.microsoft.com/en-us/library/ms537512(VS.85).aspx
Also used to create WP7 optimized sites: http://blogs.msdn.com/b/iemobile/archive/2010/12/08/targeting-mobile-optimized-css-at-windows-phone-7.aspx