.coin {
    position: absolute;
    width: 32px;
    height: 32px;
    background-image: url('../images/coin.png');
    background-size: cover;
    pointer-events: none;
    transform: translate(-50%, -50%);
    /* 讓金幣中心對準點擊位置 */
    will-change: transform, opacity;
    /* 提高動畫效能 */
}

@keyframes spin {
    0% {
        transform: translate(-50%, -50%) rotateY(0deg);
    }

    100% {
        transform: translate(-50%, -50%) rotateY(360deg);
    }
}