Change the color of background

Hello Everyone,
I need to modify the color of the HEADER background. In admired theme you can choose several skin style but the header and footer is “impossible” to change in “simple” way.

I tried to add follow code

/* Add specific style overrides below.
————————————-*/

.wp-pagenavi .current, #header, #foot_wrap {
background-color: #ffffff;

in my style.css (on the end) but doesn’t work!

I would like to have the background like this:

https://www.plugvalvefactory.com/

In this the skin style “kiss of orange” was changed but how?!?!

What could I do to change my backgroud? Which code I have to add or change in my style.css?

Thanks for any tips!
Vale

[ No bumping please. ]