There are 3 expandable sections here in order to define your Header preferences in Uranus.

Default Header:
Here, you can set the background color for the header, the menu link color, the submenu background color, the submenu link color and the top-bottom header spacing.

Dark Header:
By default, this is a transparent header. However, you can set the background color you prefer and the menu link color.

Light Header:
By default, this is another transparent header. However, you can set the background color you prefer and the menu link color.