/* ========== 全局样式 ========== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary-color: #3498db;
    --secondary-color: #e74c3c;
    --success-color: #2ecc71;
    --warning-color: #f39c12;
    --danger-color: #e74c3c;
    
    --bg-light: #f8f9fa;
    --bg-white: #ffffff;
    --text-dark: #2c3e50;
    --text-light: #7f8c8d;
    --border-color: #dee2e6;
    
    --shadow-sm: 0 2px 4px rgba(0,0,0,0.08);
    --shadow-md: 0 4px 12px rgba(0,0,0,0.1);
    --shadow-lg: 0 8px 24px rgba(0,0,0,0.12);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
    background: #ffffff;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 20px;
    line-height: 1.6;
}

.container {
    max-width: 1200px;
    width: 100%;
    background: var(--bg-white);
    border-radius: 20px;
    box-shadow: 0 2px 20px rgba(0, 0, 0, 0.08);
    padding: 40px;
    animation: fadeIn 0.5s ease;
    border: 1px solid #e9ecef;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ========== 头部 ========== */
.header {
    text-align: center;
    margin-bottom: 40px;
    padding-bottom: 20px;
    border-bottom: 2px solid var(--border-color);
}

.header h1 {
    font-size: 2.5rem;
    color: var(--text-dark);
    margin-bottom: 8px;
    font-weight: 700;
}

.subtitle {
    color: var(--text-light);
    font-size: 1rem;
}

/* ========== 主内容区 ========== */
.main-content {
    display: grid;
    grid-template-columns: 180px 1fr 180px;
    gap: 20px;
    margin-bottom: 30px;
}

/* ========== 玩家信息卡片 ========== */
.player-section {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.player-card {
    background: white;
    border-radius: 12px;
    padding: 16px;
    text-align: center;
    transition: all 0.3s ease;
    border: 2px solid #e9ecef;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
    position: relative;
    overflow: hidden;
}

.player-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, var(--primary-color), #64b5f6);
    opacity: 0;
    transition: opacity 0.3s ease;
}

.player-card.player-ai::before {
    background: linear-gradient(90deg, #ff9800, #ffb74d);
}

.player-card.active {
    border-color: var(--primary-color);
    background: linear-gradient(to bottom, #e3f2fd 0%, white 100%);
    box-shadow: 0 4px 16px rgba(52, 152, 219, 0.2);
}

.player-card.active::before {
    opacity: 1;
}

.player-card.player-ai.active {
    border-color: #ff9800;
    background: linear-gradient(to bottom, #fff8e1 0%, white 100%);
    box-shadow: 0 4px 16px rgba(255, 152, 0, 0.2);
}

.player-header {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    margin-bottom: 16px;
}

.player-header::before {
    content: '';
    width: 36px;
    height: 36px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.3rem;
}

.player-card.player-human .player-header::before {
    content: '👨';
    background: linear-gradient(135deg, #e3f2fd, #90caf9);
    box-shadow: 0 2px 8px rgba(52, 152, 219, 0.3);
}

.player-card.player-ai .player-header::before {
    content: '🎯';
    background: linear-gradient(135deg, #fff3e0, #ffb74d);
    box-shadow: 0 2px 8px rgba(255, 152, 0, 0.3);
}

.player-header h3 {
    font-size: 1rem;
    color: var(--text-dark);
    margin: 0;
}

.player-score {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--primary-color);
    margin-bottom: 10px;
    text-shadow: 0 2px 4px rgba(52, 152, 219, 0.2);
}

.player-ai .player-score {
    color: #ff9800;
    text-shadow: 0 2px 4px rgba(255, 152, 0, 0.2);
}

.player-status {
    font-size: 0.85rem;
    color: var(--text-light);
    padding: 4px 12px;
    background: var(--bg-light);
    border-radius: 20px;
    display: inline-block;
    font-weight: 500;
}

/* ========== 难度选择 ========== */
.difficulty-selector,
.first-move-selector {
    background: white;
    border-radius: 12px;
    padding: 12px;
    border: 2px solid #e9ecef;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
}

.difficulty-selector label,
.first-move-selector label {
    display: block;
    font-size: 0.85rem;
    color: var(--text-light);
    margin-bottom: 10px;
    font-weight: 600;
}

.difficulty-btns {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.diff-btn {
    padding: 8px 12px;
    border: 2px solid var(--border-color);
    background: white;
    border-radius: 8px;
    cursor: pointer;
    font-size: 0.9rem;
    font-weight: 500;
    transition: all 0.2s ease;
    color: var(--text-dark);
}

.diff-btn:hover {
    border-color: var(--primary-color);
    background: #e3f2fd;
    transform: translateX(4px);
}

.diff-btn.active {
    background: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

/* ========== 先手选择 ========== */
.first-move-btns {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.move-btn {
    padding: 10px 12px;
    border: 2px solid var(--border-color);
    background: white;
    border-radius: 10px;
    cursor: pointer;
    font-size: 0.9rem;
    font-weight: 500;
    transition: all 0.3s ease;
    color: var(--text-dark);
    display: flex;
    align-items: center;
    gap: 8px;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
}

.move-icon {
    width: 28px;
    height: 28px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 50%;
    font-size: 1.1rem;
    transition: all 0.3s ease;
}

.move-btn[data-first="player"] .move-icon {
    background: linear-gradient(135deg, #e3f2fd, #90caf9);
}

.move-btn[data-first="ai"] .move-icon {
    background: linear-gradient(135deg, #fff8e1, #ffb74d);
}

.move-btn:hover {
    border-color: var(--success-color);
    background: #f8f9fa;
    transform: translateX(4px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
}

.move-btn:hover .move-icon {
    transform: scale(1.1);
}

.move-btn.active {
    background: var(--success-color);
    color: white;
    border-color: var(--success-color);
    box-shadow: 0 4px 16px rgba(46, 204, 113, 0.3);
}

.move-btn.active .move-icon {
    background: rgba(255, 255, 255, 0.3);
    transform: scale(1.05);
}

/* ========== 游戏区域 ========== */
.game-area {
    display: flex;
    flex-direction: column;
    align-items: center;
}

.game-status {
    font-size: 1.3rem;
    color: var(--text-dark);
    margin-bottom: 24px;
    padding: 14px 28px;
    background: linear-gradient(135deg, #f8f9fa, #e9ecef);
    border-radius: 12px;
    font-weight: 600;
    min-width: 250px;
    text-align: center;
    border: 2px solid #e9ecef;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
}

/* ========== 棋盘 ========== */
.board {
    display: grid;
    grid-template-columns: repeat(3, 150px);
    grid-template-rows: repeat(3, 150px);
    gap: 0;
    margin-bottom: 30px;
    position: relative;
    background: white;
    padding: 24px;
    border-radius: 16px;
    box-shadow: var(--shadow-md);
    border: 2px solid var(--border-color);
}

.cell {
    background: transparent;
    border: none;
    border-right: 4px solid #95a5a6;
    border-bottom: 4px solid #95a5a6;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 4rem;
    font-weight: 700;
    cursor: pointer;
    transition: all 0.15s ease;
    position: relative;
    user-select: none;
}

/* 移除右侧列的右边框 */
.cell:nth-child(3),
.cell:nth-child(6),
.cell:nth-child(9) {
    border-right: none;
}

/* 移除底部行的底边框 */
.cell:nth-child(7),
.cell:nth-child(8),
.cell:nth-child(9) {
    border-bottom: none;
}

.cell:hover:not(.filled) {
    background: linear-gradient(135deg, rgba(52, 152, 219, 0.1), rgba(52, 152, 219, 0.15));
    border-radius: 8px;
}

.cell:active:not(.filled) {
    transform: scale(0.95);
    background: linear-gradient(135deg, rgba(52, 152, 219, 0.2), rgba(52, 152, 219, 0.25));
}

.cell.filled {
    cursor: not-allowed;
    pointer-events: none;
}

.cell.player-x {
    color: var(--primary-color);
    text-shadow: 0 2px 8px rgba(52, 152, 219, 0.4);
    animation: cellPop 0.3s cubic-bezier(0.68, -0.55, 0.265, 1.55);
}

.cell.player-o {
    color: var(--secondary-color);
    text-shadow: 0 2px 8px rgba(231, 76, 60, 0.4);
    animation: cellPop 0.3s cubic-bezier(0.68, -0.55, 0.265, 1.55);
}

@keyframes cellPop {
    0% {
        transform: scale(0) rotate(-90deg);
        opacity: 0;
    }
    70% {
        transform: scale(1.05) rotate(5deg);
    }
    100% {
        transform: scale(1) rotate(0deg);
        opacity: 1;
    }
}

.cell.winner {
    background: linear-gradient(135deg, rgba(255, 193, 7, 0.3), rgba(255, 152, 0, 0.3));
    border-radius: 8px;
    animation: winPulse 0.8s ease-in-out infinite;
}

@keyframes winPulse {
    0%, 100% {
        transform: scale(1);
        box-shadow: 0 0 0 0 rgba(255, 193, 7, 0.7);
    }
    50% {
        transform: scale(1.02);
        box-shadow: 0 0 0 8px rgba(255, 193, 7, 0);
    }
}

/* ========== 控制按钮 ========== */
.game-controls {
    display: flex;
    gap: 12px;
}

.btn-primary,
.btn-secondary {
    padding: 12px 32px;
    border: none;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s ease;
}

.btn-primary {
    background: var(--primary-color);
    color: white;
    box-shadow: var(--shadow-sm);
}

.btn-primary:hover {
    background: #2980b9;
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.btn-secondary {
    background: var(--bg-light);
    color: var(--text-dark);
    border: 2px solid var(--border-color);
}

.btn-secondary:hover {
    border-color: var(--text-dark);
    transform: translateY(-2px);
}

/* ========== 游戏统计 ========== */
.game-stats {
    background: white;
    border-radius: 12px;
    padding: 16px;
    border: 2px solid #e9ecef;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
}

.game-stats h4 {
    font-size: 0.95rem;
    color: var(--text-dark);
    margin-bottom: 16px;
    padding-bottom: 12px;
    border-bottom: 2px solid var(--border-color);
    font-weight: 700;
}

.stats-grid {
    display: flex;
    flex-direction: column;
    gap: 12px;
}

.stat-item {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 12px;
    background: linear-gradient(135deg, #f8f9fa, #e9ecef);
    border-radius: 10px;
    transition: all 0.3s ease;
    border: 2px solid transparent;
}

.stat-item:hover {
    transform: translateX(4px);
    border-color: var(--primary-color);
    box-shadow: 0 2px 8px rgba(52, 152, 219, 0.2);
}

.stat-icon {
    width: 44px;
    height: 44px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.8rem;
    background: white;
    border-radius: 50%;
    flex-shrink: 0;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
}

.stat-info {
    flex: 1;
}

.stat-label {
    font-size: 0.85rem;
    color: var(--text-light);
    margin-bottom: 4px;
    font-weight: 500;
}

.stat-value {
    font-size: 1.8rem;
    font-weight: 700;
    color: var(--text-dark);
    line-height: 1;
}

/* ========== 底部说明 ========== */
.footer {
    text-align: center;
    padding-top: 24px;
    border-top: 2px solid var(--border-color);
}

.footer p {
    color: var(--text-light);
    font-size: 0.95rem;
    line-height: 1.6;
}

/* ========== 弹窗 ========== */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 1000;
    align-items: center;
    justify-content: center;
}

.modal.show {
    display: flex;
}

.modal-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.6);
    backdrop-filter: blur(4px);
    animation: fadeIn 0.3s ease;
}

.modal-box {
    position: relative;
    background: white;
    border-radius: 16px;
    padding: 40px;
    max-width: 400px;
    width: 90%;
    text-align: center;
    box-shadow: var(--shadow-lg);
    animation: modalSlide 0.4s cubic-bezier(0.68, -0.55, 0.265, 1.55);
}

@keyframes modalSlide {
    from {
        transform: translateY(-50px) scale(0.8);
        opacity: 0;
    }
    to {
        transform: translateY(0) scale(1);
        opacity: 1;
    }
}

.modal-icon {
    font-size: 5rem;
    margin-bottom: 20px;
    animation: bounce 1s ease infinite;
}

@keyframes bounce {
    0%, 100% {
        transform: translateY(0);
    }
    50% {
        transform: translateY(-10px);
    }
}

.modal-box h2 {
    font-size: 1.8rem;
    color: var(--text-dark);
    margin-bottom: 12px;
}

.modal-box p {
    color: var(--text-light);
    font-size: 1.1rem;
    margin-bottom: 30px;
}

.modal-btns {
    display: flex;
    gap: 12px;
    justify-content: center;
}

/* ========== 响应式设计 ========== */
@media (max-width: 1024px) {
    .main-content {
        grid-template-columns: 1fr;
        gap: 24px;
    }

    .player-section {
        flex-direction: row;
        gap: 16px;
    }

    .player-card,
    .difficulty-selector,
    .scoreboard {
        flex: 1;
    }
}

@media (max-width: 768px) {
    .container {
        padding: 24px;
    }

    .header h1 {
        font-size: 2rem;
    }

    .board {
        grid-template-columns: repeat(3, 100px);
        grid-template-rows: repeat(3, 100px);
        gap: 8px;
    }

    .cell {
        font-size: 3rem;
    }

    .player-section {
        flex-direction: column;
    }
}

@media (max-width: 480px) {
    .container {
        padding: 20px;
    }

    .header h1 {
        font-size: 1.6rem;
    }

    .board {
        grid-template-columns: repeat(3, 85px);
        grid-template-rows: repeat(3, 85px);
        gap: 6px;
    }

    .cell {
        font-size: 2.5rem;
        border-width: 2px;
    }

    .game-status {
        font-size: 1.1rem;
        padding: 10px 20px;
    }

    .modal-box {
        padding: 30px 24px;
    }

    .modal-icon {
        font-size: 4rem;
    }

    .modal-btns {
        flex-direction: column;
    }

    .btn-primary,
    .btn-secondary {
        width: 100%;
    }
}