.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
    }
}