Rotational wave

.rotational-wave {
  animation: rotational-wave 2s ease-in-out infinite both;
}

@keyframes rotational-wave {
  0% {
    transform: rotate(0deg);
  }
  25% {
    transform: rotate(10deg);
  }
  50% {
    transform: rotate(-10deg);
  }
  75% {
    transform: rotate(10deg);
  }
  100% {
    transform: rotate(0deg);
  }
}