title: Bootstrap 4 Modal Opacity
body: <p>So i'm using Bootstrap 4 Beta and want to darken the Background when a Modal is shown. I saw a post where i just had to add the css class</p>
  
  <pre><code>.modal-backdrop.in {
      opacity: 0.5 !important;
      position: fixed;
  }
  </code></pre>
  
  <p>to my CSS file. They wrote i don't need to add the class to the div, just add it inside the CSS file. So if i just add it, it happens nothing. If i then add the class also to my modal div everything will get the opacity, even the modal itself. Does somebody know how to fix that?</p>