Bug 1021036 - Change default button color from grey to purple r=NiKo`

browser/components/loop/content/shared/css/common.css

@@ -61,7 +61,7 @@ img {
 
 .btn {
   display: inline-block;
-  background: #aaa;
+  background: #a5a;
   border: none;
   color: #fff;
   text-decoration: none;