I suggest that you change the header to be static instead of floating. Having a floating header permanently reduces the viewable area of each page by 30% on my laptop. Also, it makes the site utterly unreadable on mobile devices such as tablets and phones, because the header is incorrectly positioned and appears right in the middle of the screen.

Imagine reading a book where every page had the title of the book on the top... Doesn't make much sense.