<div class="pyonpyon">ぴょんぴょん!!</div>
body {
  padding: 64px;
}

.pyonpyon {
  width: 150px;
  text-align: center;
  padding: 8px 16px;
  background: skyblue;
  color: #ffffff;
  border-radius: 8px;
  box-shadow: 10px 8px 10px silver;
  position: fixed;
  top: 48px;
  left: 48px;

  animation: ponpon 3s forwards infinite;
  visibility: hidden;
} 

@keyframes ponpon {
  0% {
    transform: translateY(-40px);
    visibility: visible;
    opacity: 0;
    animation-timing-function: ease-in-out;
  }
  40% {
    transform: none;
    opacity: 1;
    
  }
  70% {
    transform: none;
    opacity: 1;
  }
  100% {
    transform: translateY(-40px);
    visibility: hidden;
    opacity: 0;
  }
}

External CSS

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External JavaScript

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