a.corner {
  position: fixed; 
  top: 0; 
  right: 0; 
  svg {
    fill:#e1e1e1;
    color:#000;
    position:absolute;
    top:0;
    border:0;
    right:0;
    z-index:99;
    width:4.375rem;
    height:4.375rem;
  }
  &: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);
  }
}