You currently are using the theme version, which will make the boxes change color depending on the user's site theme. They are blue to you, but to me the boxes are pink. If you want to pick a color which will stay the same no matter which theme a user has, you need to use the custom version of the template (here it is). To change the color in this version, you change the hex color code which is located throughout the coding to the # representing the color you want to appear.