$(document).ready(function() {

    $('.down-list').width($('.dropdown-menu').width() - 2);

    $('.dropdown-menu').hover(
      function() {
          $('.menu-first', this).addClass('slide-down');
          $('.down-list', this).slideDown(100);
      },
      function() {
          obj = this;
          $('.down-list', this).slideUp(100, function() { $('.menu-first', obj).removeClass('slide-down'); });
      }
    );

});