Main Menu Button Style & Menu Color Sub Header

Hi,
i am using the main navigation button (boc_nav_nutton). I would like to know if/how i can change the style to “normal or gradient” instead of outline?

I would like to add also an “icon” (fa-calender) to the nav. button. Unfortunately i did not understand how this works in the docs! Could you please help me with this issue?

Additional question:
i would like to change the color of the menu in the “sub header” while transparency mode. How can i do it?

Thx & best regards,
Adi