title: Make a DIV tag align center ONLY in responsive mode
body: <p>I have a header with three columns. </p>
  
  <pre><code>&lt;div class="thirds"&gt;
      &lt;a href="http://www.honey-do-list-services.net"&gt;&lt;img src="http://www.honey-do-list-services.net/wp-content/uploads/2013/08/honeydolistlogweb-handyman.png" align="left"&gt;&lt;/a&gt;
  &lt;/div&gt;
  &lt;div class="thirds"&gt;
      &lt;a href="http://www.honey-do-list-services.net/wp-content/uploads/2014/05/CheckAPro-1-Ramsey-4-30-14.mp3" target="_blank"&gt;&lt;img src="http://www.honey-do-list-services.net/wp-content/uploads/2014/05/dave-ramsey-endorsement-button-small.png"&gt;&lt;/a&gt;
  &lt;/div&gt;
  &lt;div class="thirds"&gt;
     &lt;a href="http://www.honey-do-list-services.net/contact-us/"&gt;&lt;img src ="http://www.honey-do-list-services.net/wp-content/uploads/2015/09/contact_iconsmhandyman.png"; align="right"&gt;&lt;/a&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>The columns are aligned individually (left, center and right). I need to have ALL of them be centered but only on a small media screen. How can I accomplish this?</p>