第三个和第四个的代码

.nav li:after{

          content:"";

          position:absolute;

          top:17px;

          right:0px;

          width:2px;

          height:16px;

          background:linear-gradient(to bottom, #f82f87,#A24,#d62b76);

        }
        
 
        
        .nav li:last-child:after {
            background:none;
        }