two different styles (in two different windows) for the same user in the same session

[Psalmist]

I want to be able to display two different styles to the same user in the same session, one style in the main window and another style in another window that will be a javascript link from my forum.

[If you wonder why, here's why. Our site is not just a forum site but it's mainly a chat site. I want to set up a widescreen interface for users who have widescreen monitors, which will have the chat app on one side and the forum on the other side. (The forum will be in an iframe, with a stripped down style to fit the smaller space). But I don't want that stripped down style to ever show at any other time, only inside the javascripted window that logged in users will have access to if they click the link after they log in through the default style.]

Can anyone give me any tips on how to do this (if it is possible)?

Thanks