.rocket {
    position: absolute;
    width: 80px;
    height: 140px;
    background-image: url('../images/rocket.png');
    background-size: contain;
    background-repeat: no-repeat;
    animation-timing-function: linear;
    animation-iteration-count: infinite;
}
.rocket.top { top: -120px; left: 50%; animation: down 8s infinite; }
@keyframes down { 0% { top: -120px; transform: rotate(0deg); } 100% { top: 110vh; transform: rotate(360deg); } }
.rocket.bottom { bottom: -120px; left: 30%; animation: up 10s infinite; }
@keyframes up { 0% { bottom: -120px; transform: rotate(0deg); } 100% { bottom: 110vh; transform: rotate(-360deg); } }
.rocket.left { left: -120px; top: 40%; animation: right 12s infinite; }
@keyframes right { 0% { left: -120px; transform: rotate(0deg); } 100% { left: 110vw; transform: rotate(360deg); } }
.rocket.right { right: -120px; top: 60%; animation: left 14s infinite; }
@keyframes left { 0% { right: -120px; transform: rotate(0deg); } 100% { right: 110vw; transform: rotate(-360deg); } }