[Theme:TwentyFourteen] Navbar has moved.

Hi. https://www.gamertime.co.uk

My navbar used to be under the header image and then when i scrolled down the page it would stay at the top. Now it is floating around the page and i cant find out how to move it. I dont think i have added any code that affects the nave bar. I did add some to my custom CSS on wordpress but it is gone now and i have tried revising the CSS and its still causing issues.

Thanks,

Mike