css--让箭头动起来

 //浅色蓝箭头
      .arr_l{
        width: 30px;
        height: 25px;
        background: url(‘./images/page_zj/sjq.png‘) no-repeat;
        background-size: 100% 100%;
        position: absolute;        
        
      }
      .arr_l1{
          left:340px;
          animation: Updown 1.5s linear 0s infinite;
      }
      .arr_l2{
          left:844px;
          animation: Updown 1.5s linear 0s infinite;
      }
      .arr_l3{
          left:1365px;
          animation: Updown 1.5s linear 0s infinite;
      }

//浅蓝色三角
@keyframes Updown {
0% { top: 855px; }
100% { top: 1120px; }
}