jQuery(document).ready(function () {  
  

//Append a div with hover class to all the LI  
jQuery("div.box").append('<div class="hover"></div>');
  
  
jQuery('div.box').hover(  
          
    //Mouseover, fadeIn the hidden hover class
    function() {
        jQuery(this).children('div').stop(true, true).fadeIn('1000');
         },

         //Mouseout, fadeOut the hover class
         function() {

         jQuery(this).children('div').stop(true, true).fadeOut('1000');
    });
});