It would involve some custom PHP code in order to do that – I’m away from the office so I can’t provide it – but if you’d like it I can provide once I get home on Monday.
You can also try setting the Navigation Position in “Customize > Layout” to float right.
Then you can remove the navigation background from the navigation and set up your header element with the same color.
That will achieve the same sort of look.
Let me know 🙂