function slideSwitch() {
 var $active = $('.banner img.active');
 if ( $active.length == 0 ) $active = $('.banner img:last');
 var $next =  $active.next().length ? $active.next() : $('.banner img:first');
  $active.addClass('last-active');
  $next.css({opacity: 0.0}).addClass('active').animate({opacity: 1.0}, 2100, function() {
  $active.removeClass('active last-active');
 });
}