title: separating spans to two lines in panel heading when on mobile
body: <p>I have a panel with a panel heading like this below and I'm trying to figure out how to get it to split into two lines when on mobile &lt; 480px and one line when greater then 480px</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
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  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;div class="panel panel-default" style="border: 1px solid lightgrey;"&gt;
    &lt;div class="panel-heading" style="text-align: center; font-size: 1.2em; color: #777;"&gt; 
  &lt;span&gt;panel heading text&lt;/span&gt;&lt;span&gt; more text&lt;/span&gt;
     &lt;/div&gt;
    &lt;div&gt;
    &lt;/div&gt;
  &lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>