[Zope] ZStylesheet multiple browser question

I am new to ZStyleSheet. How do I create a rule which is different for, say, IE and Netscape? E.g. If I want a color to be red in IE and blue everywhere else (just an example :-) I can't do it in the same rule as attribute ids have to be unique, but they are also the name of the selector attribute. Is it right to create two rules (myclass_ie and myclass_everythingelse) or is there a better way? Thanks in advance Neil