No Problem, if you want to use a different color, simply remove the design change at System > Design. Then go to System > Configuration. On the left hand side menu under General click on “Design”. Once page loaded you will see different tabs (Package, Theme, HTML Head…etc). In the Theme tab, in “Default” type “hellosimple” and this is important. In “Skin (Images / CSS)” type in “hellosimple_green”.