@keyframes fadeIn {
    from { opacity: 0; }
    to   { opacity: 1; }
}

/*
    10-second unified breathing + lighting cycle:
    - At full expansion: scale 108%, brightness 100%
    - At full contraction: scale 100%, brightness 50%
*/
@keyframes breatheAndDim {
    0% {
        transform: scale(1);
        filter: brightness(0.50);
    }

    50% {
        transform: scale(1.08);
        filter: brightness(1);
    }

    100% {
        transform: scale(1);
        filter: brightness(0.50);
    }
}