title: how to change ngBootstrap datepicker border-radius
body: <p>I want to set the border-radius of the ngBoostrap datepicker to 0.</p>
  
  <p>CSS:</p>
  
  <pre><code>[_nghost-c9] {
     border-radius: 0.25rem;
  }
  </code></pre>
  
  <p>HTML:</p>
  
  <pre><code>&lt;ngb-datepicker _ngcontent-c7="" tabindex="0" _nghost-c9="" class="ng-untouched ng-pristine ng-valid"&gt;
  &lt;/ngb-datepicker&gt;
  </code></pre>
  
  <p>I don't want to change any code of ngBootstrap. Is there a method on how to override this css?</p>