Integrating other CSS with Majestic + an issue

So I'm wondering: How do we integrate other CSS with Majestic?

I'd like to have the Tabbed Menu CSS colours also change along with the theme

Also I have an issue. When users for example close the browser and reopen it, the background and width don't save - Only the colour.

Any assistance would be awesome!

Oh, and if the error needs any file changes please PM them to me, as I don't want to reinstall