/* ------------------------------------------
 * IT书包
 * 网址：www.itshubao.com
 * 整理：yinq<3331653644@qq.com> 
 -------------------------------------------- */
BODY {
  -webkit-perspective: 40em;
          perspective: 40em;
  -webkit-perspective-origin: center center;
          perspective-origin: center center;
  overflow: hidden;
  font-size: 14px;
  background: #000;
  background-image: -webkit-linear-gradient(left, rgba(255, 255, 255, 0.025) 50%, transparent 50%);
  background-image: linear-gradient(to right, rgba(255, 255, 255, 0.025) 50%, transparent 50%);
  background-size: 2rem 100%;
}

.container {
  width: 10em;
  height: 10em;
  -webkit-transform-style: preserve-3d;
          transform-style: preserve-3d;
  -webkit-animation: rotate 12s infinite linear;
          animation: rotate 12s infinite linear;
}

.cube {
  position: absolute;
  width: 10em;
  height: 10em;
  -webkit-transform-style: preserve-3d;
          transform-style: preserve-3d;
}
.cube--2 {
  -webkit-transform: rotateX(45deg) rotateY(45deg);
          transform: rotateX(45deg) rotateY(45deg);
}
.cube--3 {
  -webkit-transform: rotateX(45deg) rotateZ(45deg);
          transform: rotateX(45deg) rotateZ(45deg);
}

.side {
  position: absolute;
  width: 10em;
  height: 10em;
  border: 2px dotted rgba(255, 213, 0, 0.35);
  border-radius: 50%;
  -webkit-transform-style: preserve-3d;
          transform-style: preserve-3d;
  -webkit-transform: rotateY(180deg);
          transform: rotateY(180deg);
}
.side::before, .side::after {
  content: "";
  display: block;
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  top: 0;
  margin: auto;
  box-sizing: border-box;
  border-radius: inherit;
  border: 1px solid;
  box-shadow: inset 0 0 2em, 0 0 2em;
}
.side::before {
  width: 2.5em;
  height: 2.5em;
  color: gold;
}
.side::after {
  width: 1.5em;
  height: 1.5em;
  -webkit-transform: translateZ(-2em);
          transform: translateZ(-2em);
  box-shadow: inset 0 0 1em, 0 0 1em;
  color: teal;
}

.side--back {
  -webkit-transform: translateZ(-5em) rotateY(180deg);
          transform: translateZ(-5em) rotateY(180deg);
}

.side--left {
  -webkit-transform: translateX(-5em) rotateY(-90deg);
          transform: translateX(-5em) rotateY(-90deg);
}

.side--right {
  -webkit-transform: translateX(5em) rotateY(90deg);
          transform: translateX(5em) rotateY(90deg);
}

.side--top {
  -webkit-transform: translateY(-5em) rotateX(90deg);
          transform: translateY(-5em) rotateX(90deg);
}

.side--bottom {
  -webkit-transform: translateY(5em) rotateX(-90deg);
          transform: translateY(5em) rotateX(-90deg);
}

.side--front {
  -webkit-transform: translateZ(5em);
          transform: translateZ(5em);
}

.side__inner {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  top: 0;
  width: 5em;
  height: 5em;
  margin: auto;
  border-radius: inherit;
  border: 1px solid;
  box-shadow: inset 0 0 2em;
  color: orangered;
  -webkit-transform: translateZ(2em);
          transform: translateZ(2em);
  -webkit-transform-style: preserve-3d;
          transform-style: preserve-3d;
}
.side__inner::before, .side__inner::after {
  content: "";
  display: block;
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  top: 0;
  margin: auto;
  box-sizing: border-box;
  border-radius: inherit;
  border: 1px solid;
  box-shadow: inset 0 0 2em, 0 0 2em;
}
.side__inner::before {
  width: 2.5em;
  height: 2.5em;
  -webkit-transform: translateZ(2em);
          transform: translateZ(2em);
  color: crimson;
}
.side__inner::after {
  width: 1.5em;
  height: 1.5em;
  -webkit-transform: translateZ(4em);
          transform: translateZ(4em);
  color: purple;
}

@-webkit-keyframes rotate {
  100% {
    -webkit-transform: rotateX(360deg) rotateY(720deg) rotateZ(360deg);
            transform: rotateX(360deg) rotateY(720deg) rotateZ(360deg);
  }
}

@keyframes rotate {
  100% {
    -webkit-transform: rotateX(360deg) rotateY(720deg) rotateZ(360deg);
            transform: rotateX(360deg) rotateY(720deg) rotateZ(360deg);
  }
}
HTML, BODY {
  height: 100%;
}

BODY {
  display: -webkit-box;
  display: -ms-flexbox;
  display: flex;
  -webkit-box-pack: center;
      -ms-flex-pack: center;
          justify-content: center;
  -webkit-box-align: center;
      -ms-flex-align: center;
          align-items: center;
}