<script>
            $('a').click(function(){
$('.window').css("display","none");
            });
        </script>
<div id="popup">
  <div id="dialog" class="window">
<span class="title">
                     xxx
</span>
    <div id="popup_icerik">
      XXXX
</div>
      <div id="popupfoot">
<a href="#" class="button">Kapat</a></div>
  </div>
</div>