The Extra Theme has feature for assigning different categories a different “accent” color that is used in various places when posts of a particular category are shown. For example, it will show up in the color of the top bar in post modules, and in the star rating colors on the posts themselves.
One thing that isn’t entirely obvious is where exactly these colors can be changed.
To change the color for a particular category, go to “Posts > Categories” from your WordPress dashboard. Hover over then category you want to change the color for, and click the “Edit” link that appears.
You should see a screen like so:
Simply change the “Color” option to your choice of category highlight color and click “Update”.
If you refresh your site, it should now show with your new category color.