/* 硬币容器：提供 3D 透视 */
.coin-container {
    perspective: 1200px;
    -webkit-perspective: 1200px; /* Firefox 兼容 */
    display: inline-block;
    margin: 1.5rem auto;
}
/* 硬币本体 */
.coin {
    width: 180px;
    height: 180px;
    border-radius: 50%;
    position: relative;
    transform-style: preserve-3d;
    -webkit-transform-style: preserve-3d; /* Firefox 兼容 */
    transition: transform 0.1s ease;
    margin: 0 auto;
    cursor: pointer;
    filter: drop-shadow(0 8px 16px rgba(0,0,0,0.25));
    will-change: transform; /* 优化 3D 渲染性能 */
}
/* 硬币两面：共用样式 */
.coin-face {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    border-radius: 50%;
    backface-visibility: hidden;
    -webkit-backface-visibility: hidden; /* Firefox/Safari 兼容 */
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    border: 5px solid #b8860b;
    box-shadow: inset 0 0 20px rgba(0,0,0,0.15), inset 0 0 0 6px rgba(255,255,255,0.25);
    overflow: hidden;
    box-sizing: border-box;
}
/* 硬币内圈装饰 */
.coin-face::before {
    content: '';
    position: absolute;
    top: 8px;
    left: 8px;
    right: 8px;
    bottom: 8px;
    border-radius: 50%;
    border: 2px dashed rgba(0,0,0,0.2);
    pointer-events: none;
}
/* 正面（Heads）：金色
   translateZ(1px) 让正面稍微靠前，避免与反面深度冲突 */
.coin-heads {
    background: radial-gradient(circle at 35% 35%, #ffe066, #f0b429 60%, #d4a017);
    color: #7a5c00;
    transform: rotateY(0deg) translateZ(1px);
    -webkit-transform: rotateY(0deg) translateZ(1px);
}
/* 反面（Tails）：银色
   【关键修复】translateZ(1px) 让反面稍微靠前，避免在 Firefox 下被正面遮挡
   同时保持 rotateY(180deg) 使其朝向后方 */
.coin-tails {
    background: radial-gradient(circle at 35% 35%, #f0f0f0, #c0c0c0 60%, #a0a0a0);
    color: #4a4a4a;
    transform: rotateY(180deg) translateZ(1px);
    -webkit-transform: rotateY(180deg) translateZ(1px);
}
/* 硬币上的图案文字 */
.coin-symbol {
    font-size: 2.8rem;
    line-height: 1;
    margin-bottom: 0.2rem;
}
.coin-label {
    font-size: 1rem;
    font-weight: 700;
    letter-spacing: 3px;
    text-transform: uppercase;
}
.coin-value {
    font-size: 1.5rem;
    font-weight: 700;
    margin-top: 0.15rem;
}
/* 抛硬币过程中的旋转动画 */
.coin.flipping {
    animation: flipAnimation 1.2s cubic-bezier(0.4, 0.0, 0.2, 1) forwards;
    -webkit-animation: flipAnimation 1.2s cubic-bezier(0.4, 0.0, 0.2, 1) forwards; /* Firefox 兼容 */
}
@keyframes flipAnimation {
    0% { transform: rotateY(0deg) translateY(0); }
    25% { transform: rotateY(720deg) translateY(-60px); }
    50% { transform: rotateY(1440deg) translateY(-80px); }
    75% { transform: rotateY(2160deg) translateY(-30px); }
    100% { transform: rotateY(var(--final-rotation, 1800deg)) translateY(0); }
}
/* Firefox 需要单独的 -webkit 前缀（部分版本） */
@-webkit-keyframes flipAnimation {
    0% { -webkit-transform: rotateY(0deg) translateY(0); }
    25% { -webkit-transform: rotateY(720deg) translateY(-60px); }
    50% { -webkit-transform: rotateY(1440deg) translateY(-80px); }
    75% { -webkit-transform: rotateY(2160deg) translateY(-30px); }
    100% { -webkit-transform: rotateY(var(--final-rotation, 1800deg)) translateY(0); }
}
/* 结果文字 */
.result-text {
    font-size: 1.8rem;
    font-weight: 700;
    letter-spacing: 1px;
    min-height: 3rem;
    color: #0d6efd;
}
.result-text.heads {
    color: #d4a017;
}
.result-text.tails {
    color: #6c757d;
}
/* 统计卡片 */
.stat-card {
    background: #f8f9fa;
    border-radius: 0.75rem;
    padding: 1rem;
    text-align: center;
    border: 1px solid #e9ecef;
}
.stat-number {
    font-size: 2rem;
    font-weight: 700;
    line-height: 1.2;
}
.stat-label {
    font-size: 0.85rem;
    color: #6c757d;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}
.stat-heads .stat-number { color: #d4a017; }
.stat-tails .stat-number { color: #6c757d; }
.stat-total .stat-number { color: #0d6efd; }
/* 历史记录项 */
.history-item {
    transition: background-color 0.15s ease;
    border-left: 3px solid transparent;
}
.history-item:hover {
    background-color: #f1f3f5;
    border-left-color: #0d6efd;
}
.history-badge {
    font-weight: 600;
    padding: 0.2rem 0.6rem;
    border-radius: 0.375rem;
    font-size: 0.85rem;
}
.history-badge.heads {
    background: #fff3cd;
    color: #856404;
}
.history-badge.tails {
    background: #e9ecef;
    color: #495057;
}
/* 功能描述卡片 */
.feature-desc {
    background: #f8f9fa;
    border-left: 4px solid #0d6efd;
    padding: 0.75rem 1rem;
    border-radius: 0.5rem;
    font-size: 0.9rem;
    color: #495057;
    margin-top: 2rem;
}
.feature-desc i {
    color: #0d6efd;
}
.btn-flip {
    padding: 0.65rem 2.5rem;
    font-weight: 600;
    letter-spacing: 0.5px;
    font-size: 1.1rem;
}
.tip-text {
    font-size: 0.8rem;
    color: #6c757d;
    margin-top: 0.25rem;
}