CSS/円アニメーション

#wrap {
    position: relative;
    width: 300px;
    height: 300px;
    margin: 50px auto;
}
.circle {
    width: 300px;
    height: 300px;
    border-radius: 150px;
    background: pink;
}
 
#circleRight {
    position: absolute;
    left: 150px;
    width: 150px;
    height: 300px;
    overflow: hidden;
}
#circleRight-hidden {
    position: relative;
    left: -150px;
    width: 150px;
    height: 300px;
    overflow: hidden;
    -webkit-transform: rotate(0deg);
    transform: rotate(0deg);
    -webkit-transform-origin: 100% 50%;
    transform-origin: 100% 50%;
    -webkit-animation: rotateRight 5s linear infinite;
    animation: rotateRight 5s linear infinite;
}
@-webkit-keyframes rotateRight {
    0% {
        -webkit-transform: rotate(0deg);
        transform: rotate(0deg);
    }
    50% {
        -webkit-transform: rotate(180deg);
        transform: rotate(180deg);
    }
    100% {
        -webkit-transform: rotate(180deg);
        transform: rotate(180deg);
    }
}
@keyframes rotateRight {
    0% {
        -webkit-transform: rotate(0deg);
        transform: rotate(0deg);
    }
    50% {
        -webkit-transform: rotate(180deg);
        transform: rotate(180deg);
    }
    100% {
        -webkit-transform: rotate(180deg);
        transform: rotate(180deg);
    }
}
 
#circleLeft {
    width: 150px;
    height: 300px;
    overflow: hidden;
}
#circleLeft-hidden {
    position: relative;
    left: 150px;
    width: 150px;
    height: 300px;
    overflow: hidden;
    -webkit-transform: rotate(0deg);
    transform: rotate(0deg);
    -webkit-transform-origin: 0% 50%;
    transform-origin: 0% 50%;
    -webkit-animation: rotateLeft 5s linear infinite;
    animation: rotateLeft 5s linear infinite;
}
#circleLeft .circle {
    position: relative;
    left: -150px;
}
@-webkit-keyframes rotateLeft {
    0% {
        -webkit-transform: rotate(0deg);
        transform: rotate(0deg);
    }
    50% {
        -webkit-transform: rotate(0deg);
        transform: rotate(0deg);
    }
    100% {
        -webkit-transform: rotate(180deg);
        transform: rotate(180deg);
    }
}
@keyframes rotateLeft {
    0% {
        -webkit-transform: rotate(0deg);
        transform: rotate(0deg);
    }
    50% {
        -webkit-transform: rotate(0deg);
        transform: rotate(0deg);
    }
    100% {
        -webkit-transform: rotate(180deg);
        transform: rotate(180deg);
    }
}

.revolution .shape.a {
  animation: revolution 3s infinite linear;
  top: calc(50% - 2em);
  left: calc(50% - 9em);
  transform-origin: 10em 50%;
}
.revolution .shape.b {
  animation: revolution 6s infinite linear reverse;
  background-color: red;
  width: 2em;
  height: 2em;
  left: calc(50% - 1em);
  top: calc(50% - 1em);
}

@keyframes revolution {
  100% {
    transform: rotateZ(360deg);
  }
}
.principle {
  width: 100%;
  height: 200px;
  position: relative;
}

.shape {
  background: #2d97db;
  border: 1em solid #fff;
  width: 4em;
  height: 4em;
  position: absolute;
  top: calc(50% - 2em);
  left: calc(50% - 2em);
  border-radius: 50%;
}