title: how to customize tooltip in bootstrap 4
body: <p>Am using Bootstrap '4.0.0-alpha.6' and Im trying to update tooltip styles to customize it. Right now, Im using Bootstrap 4 and also, I added some custom css class also. But it is not responding as per my custom style while mouse hover.</p>
  
  <p>HTML</p>
  
  <pre><code>&lt;span data-toggle="tooltip" data-placement="top" title="Testing tooltip with custom style" class="red-tooltip" (click)="nodeion(node)"&gt;
      some text
  &lt;/span&gt;
  </code></pre>
  
  <p>CSS</p>
  
  <pre><code>.red-tooltip + .tooltip-top &gt; .tooltip-inner {
      background-color: #f00;
      padding: 10px;
      font-size: 14px;
  }
  </code></pre>
  
  <p>but, after this update, it is reflected as per the change, it is stil showing default style of bootstrap.
  Any help, please?</p>