Changing (only) header bgcolor and height

Hi,

I’m looking for a way to change the background color of the header (main menu) (for example white to black) without changing all the background color of the site….

I also need to resize the height of the header (with the main menu) (for example 90px to 60 px) without generating problem for the Responsive display…

Any suggestions to help me ?
Thanks for your responses !
Regards