<div class="fluffy"></div>
.fluffy {
  background: #000;
  width: 100px;
  height: 100px;
  margin: 100px;
  animation: fluffy1 3s ease infinite;
}

@keyframes fluffy1 {
  0% { transform:translateY(0) }
  5% { transform:translateY(0) }
  10% { transform:translateY(0) }
  20% { transform:translateY(-15px) }
  25% { transform:translateY(0) }
  30% { transform:translateY(-15px) }
  50% { transform:translateY(0) }
  100% { transform:translateY(0) }
}
Rerun