.github-corner {
    position: absolute;
    top: 0;
    right: 0;
    width: 80px;
    height: 80px;
    z-index: 10;
}

.github-corner svg {
    fill: #151513;
    color: #fff;
    position: absolute;
    top: 0;
    right: 0;
    border: 0;
}

.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;
    }
}