/**组件样式**/
.your-class .pic{

  padding-top: 51.6%;
  position: relative;
  overflow: hidden;}

.your-class .pic div.a {
  position: absolute;
  left: 50%;
  top: 50%;
  transform: translateX(-50%) translateY(-50%);
  width: 100%;
  height: 100%;
  transition: all 0.5s;
  background-repeat: no-repeat;
  background-position: center center;
  background-size: cover;}