[Theme: Visia] change menu/header colour

Thanks in advance if anyone can lead me up the right garden path ??

The site i working with is here >> https://unita’c1.com/newsite

1st issue; I am trying to change menu (or is it header) colour from white to grey or black in the menu. I’ve looked in both menu and header css and can’t locate colour bit.

2nd issue;
my ‘about’ doe not go anywhere when clicked from Home page menu.

3rd issue; my ‘Case Studies’ (aka portfolio page) is only displaying a section of the projects. Yet when i retag my ‘About’ page template to portfolio template it’s shows all the projects, which is what i want.

https://www.ads-software.com/plugins/menu/