[SOLVED] Banner to overlap Header image

I am working on a website http://gocabrera.com and am trying to position a banner at the top of the page. Currently it is 486 x 60 inside a widget but we would prefer to have it at 720 x 120. Placing this above the header image drives the header too low and creates a large blank space which does not look good. The solution would seem to be to find a way to place the banner or widget partially over the header image but I have no idea if this is possible or how it could be accomplished.

You can see what I mean from the following images:-



I am using the most up to date versions of WordPress and Atahualpa.

Any suggestions will be greatly appreciated.

Thanks

Adrian