Which browsers are you refering to? Safari? Mozilla? Lynx? A cellphone?
The issues invoved with creating a truly cross-browser compatible CSS layout are pretty hairy. But they are not insurmountable. It just takes a bunch of patience and testing.
I am all for a rewrite to do this. However if the HTML is scattered throughout the code there are larger issues to contend with. Maybe cleaning the codebase up first to get all the presentational markup together into one place and taking a more template oriented approach would be the logical first step here? I have never looked at the code so please correct me if this has already been done.