Strange thin line underneath subheader image

webbabe

I somehow have a dark thin line, across all width of the page under the subheader image, but above an image and other page element. I suspect this may be caused by some background/border/image/pixel gap and can be solved through css, but I searched and searched but cannot find the solution.

Or perhaps it is a wrapper line of some sort?

I have submitted the URL of the website through Codecanyon DM.