Fix validation errors.

_layouts/default.html

@@ -46,7 +46,7 @@
 
     <div class="bsg-contribute">
       <div class="bsg-container">
-        <iframe class="github-btn" src="http://ghbtns.com/github-btn.html?user=twbs&repo=bootstrap&type=watch&count=false&size=large" allowtransparency="true" frameborder="0" scrolling="0" width="80px" height="30px"></iframe>
+        <iframe class="github-btn" src="http://ghbtns.com/github-btn.html?user=twbs&amp;repo=bootstrap&amp;type=watch&amp;count=false&amp;size=large" width="80" height="30"></iframe>
         <p><a href="https://github.com/twbs/bootstrap-expo/issues/new" target="_blank">Suggest new sites</a> on GitHub. Subscribe to the <a href="/feed.xml" title="Bootstrap Expo RSS feed">RSS feed</a>.</p>
       </div>
     </div>

css/bootstrap-expo.css

@@ -109,6 +109,9 @@ body {
   margin-top: 20px;
 }
 
+.github-btn {
+  border-width: 0;
+}
 
 /* Ads in the listing */
 .carbonad {