title: Material Vertical Divider isn't showing up
body: <p>I made a really simple program because i wanted to try out the vertical divider provided by angular material but for some reason it's not showing up.
  My code is:</p>
  
  <pre><code>&lt;div&gt;
    &lt;span&gt;code&lt;/span&gt;
  &lt;/div&gt;
  &lt;mat-divider [vertical]="true"&gt;&lt;/mat-divider&gt;
  &lt;div&gt;
    &lt;span&gt;2&lt;/span&gt;
  &lt;/div&gt;
  </code></pre>