body {
    margin:0;
    height: 100%;
}
/* HTML: <div class="loader"></div> */
.loader {
    height: 60px;
    aspect-ratio: 1;
    --c: no-repeat linear-gradient(#fff 0 0);
    background: var(--c), var(--c), var(--c), var(--c);
    background-size: 33.4% 33.4%;
    animation: l7 1.5s infinite linear;
}

@keyframes l7 {
    0%, 5% {
        background-position: 0 0,50% 0,0 50%,50% 50%
    }

    25% {
        background-position: 0 0,100% 0,0 100%,50% 50%
    }

    50% {
        background-position: 50% 0,100% 0,0 100%,0 50%
    }

    75% {
        background-position: 50% 0,100% 50%,0 100%,0 0
    }

    95%, 100% {
        background-position: 50% 0,50% 50%,0 50%,0 0
    }
}