Use sections on user pages

I'm developing a site that will use one database to manage all of the content/users but will function as two sites. I'm using sections to create a different ui and functionality for the sub site. I'm hoping to be able to have a login/profile page for example.com/user that is the same theme as the main site, and have a different page for example.com/section/user. The pages can have the same fields, functionality, etc. Just hoping for different themes. Sections is working for everything but the user pages. I'm not sure if it's possible to have two different set of user pages, or at least themes based on the path. Any help would be greatly appreciated.