:root {
    --size: 40rem;
    --radius: calc(var(--size) * 20 / 100);
}

.image-card {
    width: var(--size);
    height: var(--size);
    border-radius: var(--radius);
    position: relative;
    background-size: cover;
    margin: calc(var(--size) * 20 / 100);
}

.image-card:before {
    content: "";
    position: absolute;
    width: 100%;
    height: 100%;
    background-image: inherit;
    background-size: cover;
    border-radius: var(--radius);
    z-index: -1;
    filter: blur(12px);
    opacity: 0.6;
    left: 50%;
    transform: translate(-50%, 0%);
}