Header issue in BlankSlate

Good morning fine folks.
I am customizing BlankSlate with a child theme, for pretty much the first time. It’s going okay, but I’m having a header issue. I don’t know where that space between my header and container is coming from. I want the tabs to butt up against the border on the container. It’s really bugging me and I’ve been over and over it. Help!
https://shinhollow.com/
Thanks!
Elaine