<div class="zoom-in-zoom-out"></div>
.zoom-in-zoom-out {
  margin: 24px;
  width: 50px;
  height: 50px;
  background: green;
  animation: zoom-in-zoom-out 2s ease-out infinite;
}

@keyframes zoom-in-zoom-out {
  0% {
    transform: scale(1, 1);
  }
  50% {
    transform: scale(1.5, 1.5);
  }
  100% {
    transform: scale(1, 1);
  }
}

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