Bootstrap iPhone menu CSS help for a large amount of menu items - Using Pagelines Framework

Site in question:

I'd like to improve the menu management for mobile devices. This site has a lot of menu items and when it expands on a phone, it goes off the page.

I was thinking the menu could stack multiple items at a time instead of the single dropdown - an example would be (but not sure of the CSS sauce for this):


About >
Bios | History | Albums | Updates

Media >
Music | Videos Photos
Tour | Merch

Contact >
Friends | Contact LRB

Has anyone else got a manageable solution for a lot of menu items like this site on a mobile device?