White area obscuring drop down nav menus under header

After changing headers files I have a full width white blank area covering my drop down menu items. I can’t see any dimensions out of size on the style sheet. It forces my first ad down the page, creating a large blank space.

https://middleschoolscience.info/

If you look under the nav bar right under the header, you can see the top of the pull down menu items. Again, it looks as though a blank white image is covering up the menus.

Thanks