title: Font Awesome 5 on pseudo elements shows square instead of icon
body: <p>I am trying to change the content of a <code>span</code> with a Font Awesome icon directly from the CSS page but can't seem to make it work properly.</p>
  
  <p>1) I have imported FA from the documentation and in the <code>&lt;head&gt;</code></p>
  
  <pre><code>&lt;link rel="stylesheet" href="https://use.fontawesome.com/releases/v5.0.9/css/all.css" integrity="sha384-5SOiIsAziJl6AWe0HWRKTXlfcSHKmYV4RBF18PPJ173Kzn7jzMyFuTtk8JA7QQG1" crossorigin="anonymous"&gt;
  </code></pre>
  
  <p>2) My html looks like this : </p>
  
  <pre><code>&lt;span class='myClass'&gt;Movies&lt;/span&gt;
  </code></pre>
  
  <p>3) Let's now say I would like to change the content of the span with an icon directly from the CSS Page.</p>
  
  <p>My css currently looks like this but it isn't working, it gives me a square instead of the icon.</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-css lang-css prettyprint-override"><code>.myClass {
    font-size:25px;
  }
  
  .myClass::after {
    font-family: 'Font Awesome 5 Free';
    content: '\f008';
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;link rel="stylesheet" href="https://use.fontawesome.com/releases/v5.0.9/css/all.css"&gt;
  &lt;span class='myClass'&gt;&lt;/span&gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p>Funny thing is that it looks like it is working with some icons. If I test with <code>content: '\f007';</code> it works. Any idea why?</p>
  
  <p>(And if you wonder why I want to change the icon directly in the CSS, it is because I am using media queries so I can't add it directly in the HTML page)</p>