Documentation for Migrating

I have a subdomain with a responsive theme. I only want to move teh design elements of the responsive theme and also have the responsive theme added to the domain where the site is going to.

i.e. I have name.domain.com setup and configured the way it looks

I have another domain called domain.com with all the posts and pages that I want.

I want to move and install the responsive theme from subdomain to domain.com without deleting posts and pages already on Domain.com

Is there a tool to do that? Or do I have to install the responsive theme and customize it manually after installed?

Hope that makes sense.

Thanks,
Mario