title: Scroll on fixed position div
body: <p>The entire popup-div is visible, and when I scroll vertically, it follows.</p>
  
  <p><img src="https://i.stack.imgur.com/DEZH1.png" alt="enter image description here"></p>
  
  <p>Only half of the popup-div is visible, and when I scroll vertically it follows, but it's impossible to view the second part of the popup-div. <strong>How can this be achieved?</strong></p>
  
  <p><img src="https://i.stack.imgur.com/fOem5.png" alt="enter image description here"></p>
  
  <p>css code:</p>
  
  <pre><code>  .popup
  {
      position:fixed;
      z-index:9002;
      background-color:#FFFFFF;
      border:solid 1px #000000;
      top: 20%;
      left: 20%;
      overflow: auto;
  }
  .popupbackground
  {
      background-color:#111;
      opacity:0.65;
      filter:alpha(opacity=65);
      position:fixed;
      z-index: 500;
      top:0px;
      left:0px;
      width: 100%;
       height: 100%;
  }
  </code></pre>
  
  <p>I'm working with ASP.NET, if the code-behind is needed to answer this question I will provide it.</p>
  
  <p>I have read about solutions such as setting the overflow parameter to auto or scroll, but haven't gotten that to work. </p>
  
  <p>Update follows below:</p>
  
  <p>Now the popup is scrollable vertically as wanted, but only if the scrollbar is visible horizontally.
  <img src="https://i.stack.imgur.com/Pqhb0.png" alt="enter image description here"></p>
  
  <p>Here, it's not possible to scroll vertically because the scrollbar is not visible, and scrolling horizontally in the browser just forces the popupdiv to follow along. </p>
  
  <p><img src="https://i.stack.imgur.com/ObqAs.png" alt="enter image description here"></p>