$(document).ready(
  function () { 
    $('#topnav').superfish({
      animation: {opacity:'show', height:'show'},
      speed: 'fast',
      autoArrows: false,
      dropShadows: true

    });
    $('#topnav li').hover(
      function () {
        $(this).addClass('active');
      },
      function () {
        $(this).removeClass('active');
      }
    );
  }
);