.wrap,
.wrap > div {
  width: 100%;
  position: absolute;
}
.wrap div .img-child,
.wrap > div {
  height: 100%;
  background-size: cover;
  background-repeat: no-repeat;
}
* {
  margin: 0;
  padding: 0;
}
body {
  height: 100%;
  overflow: hidden;
  font: 16px "微软雅黑";
}
.wrap {
  height: 100%;
}
.wrap > div {
  background-position: center center;
}
.wrap .img-01 {
  background-image: url(../img/background_1.jpg);
}
.wrap .img-02 {
  background-image: url(../img/background_2.jpg);
}
.wrap .img-03 {
  background-image: url(../img/background_3.jpg);
}
.wrap .img-04 {
  background-image: url(../img/background_4.jpg);
}
.wrap div .img-child {
  background-position: 0 0;
  display: inline-block;
  z-index: 1;
}
.img-rotate {
  animation: rotate 0.6s both;
}
@keyframes rotate {
  from {
    transform: rotateY(0);
  }
  to {
    transform: rotateY(90deg);
  }
}