body {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    overflow: hidden;
    background-color: black;
}

.div-container {
    position: relative;
    width: 500px;
    height: 643px;
    background: url('mariusz-gumienny-original.webp') no-repeat center/cover;
    overflow: hidden;
}

.div-container::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: url('mariusz-gumienny.webp') no-repeat center/cover;
    opacity: 0;
    animation: pulseAnimation 12s infinite;
    pointer-events: none;
}

@keyframes pulseAnimation {
    0% {
        opacity: 0;
    }

    50% {
        opacity: 1;
    }

    100% {
        opacity: 0;
    }
}