Logo positioned over page menu bar

Hello - first time poster, so let me first express my thanks for this amazing theme.

I've searched the forums and can't find an answer to this one.

I'd like to have the logo positioned 'over' the page menu bar, such that the logo and the menu links are horizontally aligned. I have centered the page menu bar, so the logo won't literally be on top of the menu text, but will be over the menu div.

Any help gratefully received.

Mark