title: Change hover colour of FontAwesome span icon
body: <p>I have this span:</p>
  
  <pre><code>&lt;span class="fa fa-green fa-arrow-circle-o-right" aria-hidden="true"&gt;&lt;/span&gt;
  </code></pre>
  
  <p>I changed the colour like this:</p>
  
  <pre><code>.fa-green {
      color: #008d4c;
  }
  </code></pre>
  
  <p>However, the hover function does not work:</p>
  
  <pre><code>.fa-green:hover {
      color: black;
  }
  </code></pre>
  
  <p>What's wrong?</p>