css3 下载图标动画一直播放

<style>

.aminC{

width: 30px;

height: 30px;

border-radius: 15px;

border:1px solid blue;

overflow: hidden;

}

.qwe{

width:20px ;

height: 24px;

position: relative;

margin: 0 auto;

background-image: url("./11.png");

background-size: 100% 100%;

animation: yddd 1.5s linear infinite;

-webkit-animation: yddd 1.5s linear infinite;

-ms-animation: yddd 1.5s linear infinite;

-moz-animation: yddd 1.5s linear infinite;

}

@keyframes yddd{0% {top:-24px}100% {top:30px;}}

@-webkit-keyframes yddd{0% {top:-24px}100% {top:30px;}}

@-ms-keyframes yddd{ 0% {top:-24px}100% {top:30px;}}

@-moz-keyframes yddd{0% {top:-24px}100% {top:30px;}}

</style>

<div class="aminC"><div class="qwe"></div></div>