*, *:before, *:after {
  box-sizing: border-box;
  outline: none;
}

html {
  font-family: "Source Sans Pro", sans-serif;
  font-size: 16px;
  font-smooth: auto;
  font-weight: 300;
  line-height: 1.5;
  color: #444;
}

body {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 100%;
  height: 100vh;
}
body:before, body:after {
  position: absolute;
  top: 0;
  content: "";
  width: 50%;
  height: 100%;
}
body:before {
  left: 0;
  background-color: black;
}

.container {
  position: relative;
  width: 400px;
  height: 400px;
  border-radius: 50%;
  animation: spin 3s infinite linear;
  overflow: hidden;
}
.container .yin {
  position: absolute;
  top: 0;
  left: 0;
  width: 50%;
  height: 100%;
  background-color: white;
}
.container .yin:before {
  position: absolute;
  top: 0;
  left: 50%;
  content: "";
  width: 100%;
  height: 50%;
  background: white;
  border-radius: 50%;
  z-index: 999;
}
.container .yin:after {
  position: absolute;
  top: 15%;
  left: 75%;
  content: "";
  width: 75px;
  height: 75px;
  background-color: black;
  border-radius: 50%;
  z-index: 99999;
}
.container .yang {
  position: absolute;
  top: 0;
  right: 0;
  width: 50%;
  height: 100%;
  background-color: black;
}
.container .yang:before {
  position: absolute;
  bottom: 0;
  right: 50%;
  content: "";
  width: 100%;
  height: 50%;
  background: black;
  border-radius: 50%;
  z-index: 999;
}
.container .yang:after {
  position: absolute;
  bottom: 15%;
  right: 75%;
  content: "";
  width: 75px;
  height: 75px;
  background-color: white;
  border-radius: 50%;
  z-index: 99999;
}

@keyframes spin {
  100% {
    transform: rotate(360deg);
  }
}