title: Adding a separator (a <div> or a row separator) every 3 <li>
body: <p>I'm building a site that get a JSON data and populates the site, so I get an unknown numbers of items, this items are on columns of 3, I would like that after each row to have a a nice looking line.</p>
  
  <p>When it was static content what I did was: </p>
  
  <pre><code>&lt;ul&gt;
    &lt;li&gt;&lt;/li&gt;
    &lt;li&gt;&lt;/li&gt;
    &lt;li&gt;&lt;/li&gt;
    &lt;div class="separator"&gt;&lt;/div&gt;
    &lt;li&gt;&lt;/li&gt;
    &lt;li&gt;&lt;/li&gt;
    &lt;li&gt;&lt;/li&gt;
    &lt;div class="separator"&gt;&lt;/div&gt;
  &lt;/ul&gt;
  </code></pre>
  
  <p>but now that i get the dynamic content i dont know how to manage it.</p>