cannot get header color to change in studiopress, agency child theme

I cannot find how to change the header color. I have followed nearly 50 different suggestions in these forums and it just won’t change. Can someone please tell me and show me specifically what to do? Here is the stylesheet. Apologies it is the whole thing- I don’t know where to change so I have to include whole sheet. the site isn’t live its disables so I cant include the link but the header is a shade of grey with a custom image as you will see if you know code-which I only now a bit.
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