.cell-flagged {
    background-color: transparent;
    background-image: url("image/flag1.png"), url("image/cell_hidden.png");
    background-position: center, center;
    background-repeat: no-repeat, no-repeat;
    background-size: 85%, cover;
    filter: drop-shadow(0 5px 5px rgba(145, 52, 65, 0.22));
}

.cell-flag-pop {
    animation: flagPop 280ms cubic-bezier(.18, 1.45, .32, 1);
}

@keyframes flagPop {
    0% {
        opacity: 0.35;
        transform: scale(0.56) rotate(-7deg);
    }
    62% {
        opacity: 1;
        transform: scale(1.18) rotate(3deg);
    }
    100% {
        transform: scale(1) rotate(0);
    }
}