Theme customization

Hi,
you can try the pro version:
https://www.designlabthemes.com/short-news-pro-wordpress-theme/
You will have many options for customizing colors.

Or go to Appearance » Customize page.
Click on the Additional CSS tab from the left panel.
Add this code:

/* mobile */
.mobile-navbar {background-color: #ff0000;}

/* desktop */
@media screen and (min-width: 960px) {
.header-bottom {background-color: #ff0000;}
}