festa/styles/postcard.css

.postcard {
    width: 100vw;
    height: 100vh;
    object-fit: cover;

    position: absolute;
    z-index: -1;

    user-select: none;
    pointer-events: none;
}

@media (prefers-color-scheme: light) {
    .postcard {
        filter: blur(16px) contrast(25%) brightness(175%);
    }
}

@media (prefers-color-scheme: dark) {
    .postcard {
        filter: blur(16px) contrast(50%) brightness(50%);
    }
}