.banner  ul, .banner { position: absolute; width: 100%; height: 100%; left: 0; top: 0; }
 .banner  ul { overflow: hidden; width: 100%; display: none;}
.banner li { display: none; }
.banner a { position: absolute; left: 0; top: 0; width: 100%; height: 100%; background-position: center; background-size: cover; background-repeat: no-repeat; }
.banner a:hover {opacity: 1; } 
.banner_nav {  position: absolute;  bottom: 20px; left: 50%;  margin-left: -10px;}
#index .banner_nav li {
  margin: 0 1px;  width: 20px; height: 20px; background-image: url(../img/banner_nav.png); background-size: cover; cursor: pointer;
  float: left; list-style: none; }
#index .banner_nav li.active {
  background-image: url(../img/banner_nav_active.png);
}