title: Adding multiple content CSS files to CKEditor
body: <p>How can I use more than 1 css file as content CSS with CKEditor? I already added bootstrap css in the config.</p>
  
  <pre><code>config.contentsCss = '/css/bootstrap.min.css';
  </code></pre>
  
  <p>Our designer created a 2nd css to customize some stuff and I also need to add that css file to CKEditor.</p>
  
  <p>I tried variations below, but no success so far:</p>
  
  <pre><code>config.contentsCss = '/css/bootstrap.min.css', '/css/styles.css';
  config.contentsCss = '/css/bootstrap.min.css, /css/styles.css';
  </code></pre>
  
  <p>I am using v 4.1.1</p>