Need child tabs to parent tabs

Attached is a mock up of my new site, except... I don't know how to do it! I want two master tabs that in effect, show a new website when clicked. I want everything on the site, just separated by the master tabs. Content could be accessed regardless of which "parent" tab they are on so it's really more cosmetic.

Any plugins or other ideas how to make this work?

On the sample, the Kids Magic tab is selected and all the child tabs are are for kids. If the Big Kid Magic tab was selected, the tabs would be different and feature different content.