title: How to change color of aui:button
body: <p>I have a button with aui:</p>
  
  <pre><code>&lt;aui:button type="submit" value="Update Time"
  cssClass="updatebutton"&gt;&lt;/aui:button&gt;
  </code></pre>
  
  <p>I set css class:</p>
  
  <pre><code>.updatebutton {
      color: black;
      background-color:#DDDDDD;
  }
  </code></pre>
  
  <p>But it not effect. How can I change color of aui-button</p>