possibly, Saurus, although I don’t think that using the WordPress interface that you can easily define margins top and bottom for the graphic that’s in the header, which I believe is added to the template via an admin panel.
It is possible that if datex pops the hood and look at the html of his page, he could figure out whether there’s a name for the div it’s in or for the image itself, and then in the stylesheet he can edit it so that there are appropriate margin-top and margin-bottom definitions.
But oi, that’s kludgy, and not forward-thinking; if datex redesigns the graphic at a later date to a different size, then he’ll need to redefine its placement in the CSS. I think that in this instance, creating a graphic of the proper size and “cheating” with a transparent background is the better, more forward-thinking solution.