title: CSS and fixed background not work
body: <p>I have content with an image on the right.</p>
  
  <p><a href="https://i.stack.imgur.com/JYKxa.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/JYKxa.png" alt="Image 1"></a></p>
  
  <p>My image have 950 px for height. I wish it to move at the same time as the scrooll.</p>
  
  <p>If I add this property " <strong>background-attachment: fixed;</strong> ", it works but the image is zoomed, I do not want :(</p>
  
  <p><a href="https://i.stack.imgur.com/3VGiR.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/3VGiR.png" alt="Image 2"></a></p>
  
  <p>Can you help me ? <strong>This is Fiddle :</strong></p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-css lang-css prettyprint-override"><code>body {
      background: #f2f2f2;
      font-family: Open Sans, Helvetica, Arial, Tahoma, Sans-Serif
  }
  
  /*  --------------------------------------------------
  /*  Text-transform
  /*  --------------------------------------------------
  */
  .content-image-left-right {
      background-color: #fff
  }
  
  .content-image-left-right h2 {
      margin-top: 3rem;
      margin-bottom: 3rem;
      font-weight: bold;
      letter-spacing: .4rem;
      text-align: center;
      text-transform: uppercase
  }
  
  .content-image-left-right p {
      max-width: 450px;
      color: #605e5e;
      margin-right: auto;
      margin-left: auto;
      text-align: justify
  }
  
  .content-image-left-right .cover {
      height: 550px;
      background-image: url(https://img11.hostingpics.net/pics/422842background3.png);
      background-attachment: fixed;
      background-position: center;
      background-repeat: no-repeat;
      background-size: cover
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;link href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta/css/bootstrap.min.css" rel="stylesheet"/&gt;
  
          &lt;div class='content-image-left-right'&gt;
              &lt;div class="row"&gt;
                  &lt;div class="col"&gt;
                      &lt;h2&gt;
                          Gérer
                      &lt;/h2&gt;
                      &lt;p&gt;
                          Grâce à notre solution &lt;strong&gt;complète et assistée&lt;/strong&gt;, Dometech vous permet &lt;strong&gt;une gestion simple et centralisée de tous vos biens&lt;/strong&gt;.
                      &lt;/p&gt;
                  &lt;/div&gt;
                  &lt;div class="col cover background-3"&gt;
  
                  &lt;/div&gt;
              &lt;/div&gt;
          &lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>