Deliver Theme - fixed nav/header?

Hi, this is really a great theme, only one thing missing in my opinion:
How can I get a fixed navigation/header both on desktop and mobile?
I tried but cannot figure it out.
Maybe a recipe for the cookbook section in learn.getgrav.org?

Currently Deliver does not have fixed nav/header. It shouldn't be difficult to add tho. I will check and consider adding it in next release.