<a href="/">
  <button class="bn53">Button</button>
</a>

.bn53 {
  background-color: #b81515;
  padding: 7px;
  width: 100px;
  font-family: Verdana, Geneva, Tahoma, sans-serif;
  animation: bn53bounce 4s infinite;
  cursor: pointer;
}

@keyframes bn53bounce {
  5%,
  50% {
    transform: scale(1);
  }

  10% {
    transform: scale(1);
  }

  15% {
    transform: scale(1);
  }

  20% {
    transform: scale(1) rotate(-5deg);
  }

  25% {
    transform: scale(1) rotate(5deg);
  }

  30% {
    transform: scale(1) rotate(-3deg);
  }

  35% {
    transform: scale(1) rotate(2deg);
  }

  40% {
    transform: scale(1) rotate(0);
  }
}