The theme main color can be changed from app/css/scss/_vars.scss

In this file, you will be able to see the variable “$templateColor" which is used in all the site elements. If you will change this variable color code the theme color will be changed.

$templateColor: #565656;
$hoverColor: #d72a30; 

Also, you can integrate the theme color on your elements like in the following example:

.class {color: #{$templateColor};}

In  app/css/scss/_general.scss there is also “.color-overlay" class that is used for backgrounds.