title: Add custom classname to jquery calendar cell
body: <p>I am using Jquery calendar. I am trying to insert a new class name to each cell of calendar. It gets added but it is getting removed as and when the calendar is clicked. </p>
  
  <p>Basically it refreshes the calendar on every click so newly added class is getting removed on refresh.</p>
  
  <p>How do I retain the class name?</p>
  
  <p>here is my code</p>
  
  <pre><code>$(function() {
    $('#custom-date-format').multiDatesPicker({
      dateFormat: "y-m-d"
    });
    $('.ui-state-default').addClass("calendar_bg");
  });
  </code></pre>
  
  <p><strong><a href="https://jsfiddle.net/543w1pg3/6/" rel="nofollow">Demo</a></strong></p>