Make "Download" button stand out a little more.

docs/_includes/head.html

@@ -214,9 +214,9 @@
   }
 
   .btn-outline-inverse {
-    color: #333;
+    color: #428BCA;
     background-color: transparent;
-    border-color: #333;
+    border-color: #428BCA;
     padding: 15px 30px;
     font-size: 20px;
   }