How can I extend lower the bottom of the menu bar at so that the dark blue behind the menu words extends further down the page? What CSS command is needed?

I would like to do this because currently when one scrolls down the page of the site, the words which reveal upward overlap the logo, which looks odd. Changing the logo from a transparent background to a solid one would prevent this. But to do this, and keep the current size of the logo, I would need to extend the blue color of the menu bar lower such that the bottom of the logo lines up with the bottom of the menu bar.

I'm using the OneUp One Page Parallax retina theme in dark.

Thanks for your response.