Change dashboard button color to white on hover

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

app/assets/stylesheets/framework/gitlab-theme.scss

@@ -24,6 +24,10 @@
         background-color: $color-darker;
         a {
           color: #fff;
+
+          h3 {
+            color: #fff;
+          }
         }
       }
     }