github-corner.css

.github-corner > svg {
  width: 80px;
  height: 80px;
}

.github-corner:hover .octo-arm {
  animation: octocat-wave 560ms ease-in-out
}

@keyframes octocat-wave {
  0%,
  100% {
    transform: rotate(0)
  }

  20%,
  60% {
    transform: rotate(-25deg)
  }

  40%,
  80% {
    transform: rotate(10deg)
  }
}

@media (max-width:500px) {
  .github-corner:hover .octo-arm {
    animation: none
  }

  .github-corner .octo-arm {
    animation: octocat-wave 560ms ease-in-out
  }
}