title: How to vertically center a dynamic height fixed element?
body: <p>I'm making an overlay window thing and I'm trying to vertically center the message in the center of the screen.... this is my CSS thus far:</p>
  
  <pre><code>#overlay {
      position: fixed;
      right: 0;
      left: 0;
      width: 276px;
      margin: 0px auto;
      padding: 12px 16px;
      font-size: 14px;
      color: #6d748b;
      background-color: #fff;
      border: 2px solid #b9c1d6;
      -moz-border-radius: 5px;
      -webkit-border-radius: 5px;
      border-radius: 5px;      
      z-index: 7500;
  }
  </code></pre>