Supreme header image issue with wide monitor

Hi,
I’ve recently got a new monitor that is 1920 wide. I’ve noticed that Supreme theme’s scaling of header image to be a max of 1600 wide means there will blank areas either side of my header image for any user with a monitor wider than 1600.
This problem isn’t too bad on the homepage because the featured image is behind the header area, however, on every other page I get a couple of blank areas either side of the header image.
Can you advise if it’s possible to either a) get around the Supreme theme limit and upload a header image wider than 1600 (when I attempted this using the “appearance/customise” option it wants to scale the image to be no more than 1600), or b) add a colour background to the site-header area only (the only way I’ve been able to to do this so far is change the whole page & I don’t want to do that, or c) change it so that the logo and header menu don’t go wider than 1600.
Hope this makes sense. 🙂
Cheers.