I don`t mix my css appearance attributes with my css position attributes. So for the same div I`d have two entries, one for the appearance and one for the position. Mind you, this is only for the more complicated layouts. If it`s a simple layout, then yes, I make one css sheet, and I have been known to mix. But when you have multiple and/or optional css files that an end user will be accessing by adding a suffix through a user interface, it just makes more sense to keep them separate.
I think I am not being very clear, sorry. I`ll blame it on lack of sleep. I am using separate style sheets for the different browsers because it allows me to not use hacks at all - I don`t make a style sheet just for hacks...that would be silly. <L> It`s just the strange and unusual way that works best for strange and unusual me.