.dv {
background-color: pink;
height: 160px;
width: 100px;
border-radius: 10px;
animation-name: identifier;
//动画时长
animation-duration: 1.2s;
//动画速度曲线 ease 默认，linear，ease-in，ease-out，ease-in-out，cubic-bezier(n,n,n,n) n:0-1
animation-timing-function: ease-in;
//播放次数 n，infinite
animation-iteration-count: infinite;
//是否反向播放 normal，alternate
animation-direction: alternate;
}

@keyframes identifier{
0% {
height: 160px;
}

100% {
height: 0px;
}
}