need to find include php script

I’m using some css technique which doesn’t work in some firefox versions, so I want to catch browser version & insert some css only to some specific versions.

I found php script which identify browser version. But I need to find out where I can insert this script? is there any root php file which always access?

thanks in advance

The cleaner way of doing it is through PHP. You can get and parse a useragent and feed the proper CSS file.

BTW, it is strange that firefox versions differ THAT much in CSS output, unless you are catering to some really old firefox 2 or 1. The good thing is that firefox is self-updating and most users have at least version 3.

You would insert that file of yours to /skins/your-skin-name/customer/index.tpl