I’ve got the mobile nav about 90% where I want it, but there’s still a little gap between the first dropdown and the hearder bar above it. I’m done messing with it for the moment, but I shall prevail!
Your header wrapper is the culprit. You have it set to 30px. This is causing it to be larger than the navbar and is creating that space which is what the blue is coming through. I set it to 25px but not sure if for responsive screens that would have to be tweaked more.