head {
  font-family: Impact;
}
body {
  background-color: black;
  color: white;
  font-family: Verdana;
}
@keyframes sway {
      0% { transform: translateY(0); }
      50% { transform: translateY(-20px); }
      100% { transform: translateY(0); }
    }
    
  .sway {
    animation: sway 3s ease-in-out infinite;
    animation-duration: 3s;
    animation-timing-function: ease-in-out;
    animation-delay: 0s;
    animation-iteration-count: infinite;
    animation-direction: normal;
    animation-fill-mode: none;
    animation-play-state: running;
    animation-name: sway;
    display: block;
    margin: 20px auto;
}