If you want to change the color, go to 'Pages and Themes' in the dashboard and click on customize next to the theme. Then click where it says 'Add Your CSS' and add the following line in the popup box '@import url(css/{color-name}.css);' and then click ok and then save. Instill comes with the following colors: red, green and blue. If you want to switch back, just remove that line and save it, and it will go back to the original color.