html5怎样做出图片转圈的动画效果

<img src="images/circle.png" alt="" id="circle"/>
@mixin ani-btnRotate{
 @keyframes btnRotate{
 from{transform: rotateZ(0);}
 to{transform: rotateZ(360deg);}
 }
}
@include ani-btnRotate;
#circle{
 position: absolute;
 left: 50%;
 width: REM(338);
 height: REM(338);
 margin-top: REM(200);
 margin-left: REM(-338/2);
 transform-origin: center center ;
 animation: btnRotate 1s 1s linear forwards;
 }