Since it is more a web design issue, you're probably better off looking for a website template to replace the HTML frontend. ThemeForest is a good place to look for mobile responsive templates. Here's the section for forums: http://themeforest.net/category/forums - http://themeforest.net/category/forums.
Might be a PITA to copy over the ASP code, but worth it in the long run for a really smart-looking design.
I use them for my own websites, as it saves me having to worry about getting the pretty bits and the mobile-friendly bits right. That then frees me to focus on the backend, knowing that, even if I break the site, it will do so gracefully :p