remove space above header

Hi there! Loving this theme, first off. My question: I've chosen a fixed header image, removed the "site title" and "tag line", removed the social media icons and search bar above header, but it still shows a thin white line (about 1/4 inch) above the image. I've also tired resetting the Top Header Margin to 0px, -10px, 30px, etc. but nothing seems to help. Any ideas? My site is not live yet, so I'm not sure how to show you what I mean. Sorry. Thanks for any help you can give, Kady