Line under Buger Menu

Hey. 
There is this line under my Nav-Bar (Burger Menu) and I can't get rid of it.
Would really appreciate someone helping me fix this. Can't find any information on this topic, except for changing the browser (which didn't work).

www.stunk.info
pass: 4204200

Thanks!

This worked for me:

 

.header-nav-wrapper a {
    background-image: none !important;
}