Allow for adjusting header height more easily

[DeltaRazero]

Currently trying to make a header with a lower or higher height is a very frustrating process. I would suggest for a method that would make it more accesible for people to adjust the height. It's a small nitpick though.

When making the height bigger, the backdrop element / background color for focused buttons doesn't scale.
Making the header height smaller results in header elements not vertically centering themselves in the actual height of the header.