.gallery{
    --d:8s;
    display: grid;
    overflow: hidden;
    width: 100%;    
}

.gallery >img{
    grid-area: 1/1;
    width: 80%;
    aspect-ratio: 1.5;
    object-fit: cover;
    animation: r var(--d) linear infinite;
}
.gallery > img:nth-child(2){
    animation-delay: calc(-0.2*var(--d));
}

.gallery > img:nth-child(3){
    animation-delay: calc(-0.4*var(--d));
}

.gallery > img:nth-child(4){
    animation-delay: calc(-0.6*var(--d));
}

.gallery > img:nth-child(5){
    animation-delay: calc(-0.8*var(--d));
}
@keyframes r{
    80%{
        transform: translate(-400%);
    }
    80.01%{
        transform: translate(100%);
    }
}