Hi! How to make the desired background color or background image via custom css? I entered a line there:

header body {
 background-color: #CC3300;
}

 but it did not help.

That is probably because header is child of body.
body {background-color: #CC3300;}

Thanks, but it did not help.

This full list of my custom css:

header .nav a.publish { background: red; border-color: red;};
body {background-color: #CC3300;}

First line is working.

@alex7070
If you define this:
body {background:red;}
body {background:green;}

Background color will be green, as first line is overwritten. This is happening in your case. Open browser console, click to inspect element... there is many guides on internet how to use browser in such cases.

Thanks, this works. But the top of the screen and the category section are of a different color. Is it possible to make the upper part of the site and the category section also green?

@alex7070
As I told, first check CSS basics.
That element has already background color and will of course be above body tag.

Thanks, I'll watch. It would be nice if the Sigma theme was more customizable through the admin panel.