Use solid color and transition to red color on hover

public/resources/css/module/_footer.scss

@@ -89,9 +89,10 @@
     }
 
     .styleguide-trigger {
+      color: $darkgrey;
       text-decoration: none;
-      opacity: .24;
       float: right;
+      transition: color .3s;
 
       @include respond-to('mobile') {
         display: block;
@@ -100,6 +101,10 @@
         float: none;
       }
 
+      &:hover {
+        color: $red-600;
+      }
+
       .icon-favorite {
         line-height: 20px;
       }