.flip-coin-container {
    margin: 2rem auto;
    max-width: 300px;
    text-align: center;
}
.flip-coin-area {
    margin: 2rem auto;
    position: relative;
    width: 100px;
    height: 100px;
}
.flip-coin-coin {
    width: 100%;
    height: 100%;
    position: absolute;
    transform-style: preserve-3d;
    transition: transform 3s;
}
.flip-coin-heads, .flip-coin-tails {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    border-radius: 50%;
    box-shadow: 0 0 15px rgba(0, 0, 0, 0.1);
}
.flip-coin-heads {
    background-image: url('../image/head.png');
    background-size: cover;
}
.flip-coin-tails {
    background-image: url('../image/tail.png');
    background-size: cover;
    transform: rotateY(180deg);
}
.flip-coin-flipped {
    transform: rotateY(180deg);
}
.flip-coin-flipping {
    transform: rotateY(calc(var(--rotations, 1) * 3600deg));
}