Hi David,
Thx for your speedy reply. The normal nav is managed by beaver themer however once the sticky nav comes up it seems to be controlled by the theme. I may be wrong but the way I figured this out was by adjusting the menu item height in the customizer and this adjusts the sticky navbar height on the site as well as eg the hover bg color is managed via the customizer.
My question was basically more around the point of, is the formatting ie colors, of the sticky header, managed via the customizer or only via CSS?