.plane{position:absolute;top:20%;transform:translateY(-50%) translateX(100vw) rotate(0deg);animation:fly-across 10s linear infinite;width:200px}@keyframes fly-across{0%{transform:translateY(-30%) translateX(100vw) rotate(0deg)}30%{transform:translateY(-10%) translateX(40vw) rotate(5deg)}40%{transform:translateY(-50%) translateX(30vw) rotate(10deg)}70%{transform:translateY(-100%) translateX(-10vw) rotate(5deg)}100%{transform:translateY(-100%) translateX(-100vw) rotate(0deg)}}@media (max-width:768px){.plane{width:100px}}