[Zope] Browser-Check with getBrowser(): set global var for request or call it in every html-page

Hi, i want to load different css for mozilla an explorer and found the nice function getBrowser() on zope.org. But know I don't know, what is possible or the better way to use it. 1.) my idea is to call it from my index.html and set a cookie or if possible a global var in zope for the request and use <dtml-if> for loading the css 2.) i use it to create the right css in a python script 3.) i call it in every html-header over <dtml-let> and use <dtml-if> for loading the right css what is the best to fit to zope? Thanks...Patrick