css3动画 keyframe animation

<div class="box" ></div>

@keyframes move{
  0% {width: 100px;}
  50% {width: 200px;}
  100%{width: 100px;}
}
@-webkit-keyframes move{
  0% {width: 100px;}
  50% {width: 200px;}
  100%{width: 100px;}
}

.box{
  width: 100px;
  height: 100px;
  background-color: red;
  margin: 300px 100px;

  &:hover{
    animation: move 2s;
    -webkit-animation: move 2s;
  }

}