<div></div>

div {
  background: #2db34a;
  border-radius: 50%;
  height: 50px;
  position: absolute;
  width: 50px;

  animation: shake .5s ease-in-out infinite;

}


@keyframes shake {
  0% {
    transform: translateX(0);
  }

  20% {
    transform: translateX(-10px);
  }

  40% {
    transform: translateX(10px);
  }

  60% {
    transform: translateX(-10px);
  }

  80% {
    transform: translateX(10px);
  }

  100% {
    transform: translateX(0);
  }
}