<script src="https://kit.fontawesome.com/75227c97a9.js" crossorigin="anonymous"></script>

<div>
<i class="fas fa-moon fa-7x"></i>
</div>
div{
   text-align: center;
}

.fa-moon{
   color: #edf28a;
   animation: shading 3s linear 0s infinite normal;
}

@keyframes shading {
  0% {
    opacity: 0;
  }

  100% {
    opacity: 1;
  }
}

External CSS

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External JavaScript

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