title: Overlay div block with the image while AJAX loading
body: <p>I know this is easy task and very common, but I cannot figure out how to do this ! It seems five minute task, but I have spent more than an hour... I am stupid I know.<br>
  But nevertheless, please help me to implement this.<br>
  I have div container block   </p>
  
  <pre><code>&lt;div class="wrapper_div"&gt;
  //some other divs here
      &lt;/div&gt;
  </code></pre>
  
  <p>And CSS style    </p>
  
  <pre><code>.wrapper_div{
  
      margin: auto;
  
      width: 1000px;
  
      height: 545px;
  
  }
  </code></pre>
  
  <p>Looks very simple, but I cannot overlay this div when making AJAX request.<br>
  I need to simply show loader animation (gif) at the center of this div block and overlay this block with grey background for instance.<br>
  That's all what I want, please help.    Thank you</p>
  
  <p><strong>EDIT</strong></p>
  
  <p>Sorry for such explanation, the problem is not in AJAX but in css and html layout, I cannot figure out how to create correct layout</p>