White Space under Header Image on iPhone

My header image (1000px x 200px) shows up as expected on Firefox and IE on my computer, but on my iPhone, there is a small amount of white space between it and the menu bar. I have tried various things in the custom CSS under appearance > theme options, but nothing has worked. My URL is www.dontforgetsnacks.com The help provided on this forum is great! Really appreciated by newbies like me.