How to change style of root menu bar

[Chase]

Hello,

I'm encountering a problem figuring out how to change the look and feel / style of the root menu bar. I have my items styled correctly, but I'm not sure how to change the actual style of the base menu bar.

Here is an image : http://imgur.com/AVvZOHF - I want to change the hover image on the right to represent more so my normal menu bar on the left.

Thank you for the insight.