div {border: 1px solid white; padding: 5px; aspect-ratio: 1; width: fit-content; animation: r 10s ease-in-out infinite;}
@keyframes r {
    70% { transform: rotate(90deg);}
    100% { transform: rotate(90deg);}
}

html, body  { height: 100%;}
body {
    background: #000;
    display: grid;
    place-content: center;
}
article { transform: rotate(45deg);}