.nav_main{background: #ffedc1;}
.nav_main .nav li {width:25%;}
.nav_main .nav li a:after{visibility: hidden;}
.nav_main .nav li a.aLink{width:100%;color:#e80000;font-size:23px;}
.nav_main .nav li ins {
 
  display: block;
left: 100%;
    top: 0;
    position: absolute;
  height: 68px;
  width: 2px;
  background: url(https://20da.aust.edu.cn/static/images/m.jpg);
  float: left;}