title: How to use aria-expanded="true" to change a css property
body: <p>I want to use <code>aria-expanded="true"</code> to change a css property like an active class :</p>
  
  <pre><code>&lt;li class="active"&gt;
     &lt;a href="#3a" class="btn btn-default btn-lg" data-toggle="tab" aria-expanded="true"&gt; 
         &lt;span class="network-name"&gt;Google+&lt;/span&gt;
     &lt;/a&gt;
  &lt;/li&gt;
  </code></pre>
  
  <p>I want the <code>&lt;a&gt;</code> to <code>background-color: #42DCA3</code> but only when <code>aria-expanded="true"</code>.</p>