style.css

* {
  box-sizing: border-box;
}

body {
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  margin: 0;
  overflow: hidden;
}

.btn {
  color: white;
  background-color: hsl(200, 100%, 50%);
  border: none;
  outline: none;
  padding: 0.5em 1em;
  border-radius: 0.3em;
  cursor: pointer;
}

.btn:hover {
  animation: blink 500ms ease-in-out infinite, grow 1s ease-in-out infinite;
}

.btn:focus {
  animation: fly-away 1s ease-in-out forwards;
}

@keyframes blink {
  0% {
    opacity: 1;
  }

  50% {
    opacity: 0.75;
  }

  100% {
    opacity: 1;
  }
}

@keyframes grow {
  0% {
    transform: scale(1);
  }

  50% {
    transform: scale(1.1);
  }

  100% {
    transform: scale(1);
  }
}

@keyframes fly-away {
  33% {
    transform: translate(100px, 50px) rotate(30deg) scale(0.9);
  }

  66% {
    transform: translate(0, 25px) rotate(90deg) scale(0.75);
  }

  100% {
    transform: translate(-100px, -75px) rotate(200deg) scale(0.25);
  }
}