title: CSS horizontal centering of a fixed div?
body: <pre><code>#menu {
      position: fixed;
      width: 800px;
      background: rgb(255, 255, 255); /* The Fallback */
      background: rgba(255, 255, 255, 0.8);
      margin-top: 30px;
  }
  </code></pre>
  
  <p>I know this question is a million times out there, however I can't find a solution to my case.
  I've got a div, which should be fixed on the screen, even if the page is scrolled it should always stay CENTERED in the middle of the screen!</p>
  
  <p>The div should have <code>500px</code> width, should be <code>30px</code> away from the top (margin-top), should be horizontally centered in the middle of the page for all browser sizes and should not move when scrolling the rest of the page.</p>
  
  <p>Is that possible?</p>