:root {
    --primary-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --secondary-gradient: linear-gradient(135deg, #11998e 0%, #38ef7d 100%);
    --info-gradient: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
    --warning-gradient: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    --primary-color: #667eea;
    --secondary-color: #764ba2;
    --success-color: #11998e;
    --info-color: #4facfe;
    --warning-color: #f5576c;
    --text-primary: #333;
    --text-secondary: #666;
    --text-muted: #999;
    --bg-light: #f8f9fa;
    --bg-white: #ffffff;
    --border-color: #e9ecef;
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.08);
    --shadow-md: 0 5px 15px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 30px rgba(0, 0, 0, 0.15);
    --shadow-xl: 0 20px 60px rgba(0, 0, 0, 0.2);
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 16px;
    --radius-xl: 24px;
    --radius-full: 50%;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

@media (max-width: 768px) {
    html {
        font-size: 15px;
    }
}

@media (max-width: 576px) {
    html {
        font-size: 14px;
    }
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Helvetica Neue', Arial, sans-serif;
    background-color: var(--bg-light);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    overflow-x: hidden;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    width: 100%;
}

@media (max-width: 768px) {
    .container {
        padding: 0 15px;
    }
}

@media (max-width: 576px) {
    .container {
        padding: 0 12px;
    }
}

.navbar {
    box-shadow: var(--shadow-sm);
    background: var(--primary-gradient) !important;
    border: none;
    padding: 12px 0;
}

.navbar-brand {
    font-size: 1.5rem;
    font-weight: 700;
    color: #fff !important;
}

.navbar-toggler {
    border-color: rgba(255, 255, 255, 0.3);
}

.navbar-toggler-icon {
    background-image: url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 30 30'%3e%3cpath stroke='rgba%28255, 255, 255, 0.8%29' stroke-linecap='round' stroke-miterlimit='10' stroke-width='2' d='M4 7h22M4 15h22M4 23h22'/%3e%3c/svg%3e");
}

.nav-btn {
    padding: 8px 20px;
    font-size: 0.9rem;
    font-weight: 500;
    border-radius: 25px;
    transition: all 0.3s ease;
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    gap: 8px;
    border: none;
    cursor: pointer;
}

.nav-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2);
}

.navbar .btn-light {
    color: var(--primary-color);
    background-color: #fff;
    border: 1px solid transparent;
}

.navbar .btn-light:hover {
    background-color: #f0f0f0;
    color: var(--secondary-color);
    box-shadow: 0 4px 12px rgba(102, 126, 234, 0.3);
}

.navbar .btn-outline-light {
    color: #fff;
    border: 2px solid rgba(255, 255, 255, 0.6);
    background: transparent;
}

.navbar .btn-outline-light:hover {
    background-color: rgba(255, 255, 255, 0.1);
    color: #fff;
    border-color: #fff;
}

@media (max-width: 991px) {
    .navbar-nav {
        margin-top: 15px;
    }
    
    .nav-btn {
        width: 100%;
        justify-content: center;
        margin-bottom: 8px;
    }
}

.hero-section {
    padding: 60px 0;
    background: var(--primary-gradient);
    min-height: calc(100vh - 200px);
    display: flex;
    align-items: center;
    margin: -20px 0 0 0;
    width: 100vw;
    position: relative;
    left: 50%;
    right: 50%;
    margin-left: -50vw;
    margin-right: -50vw;
}

.hero-section > .row {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

@media (max-width: 768px) {
    .hero-section {
        padding: 40px 0;
        min-height: auto;
    }
    
    .hero-section > .row {
        padding: 0 15px;
    }
}

@media (max-width: 576px) {
    .hero-section {
        padding: 30px 0;
    }
    
    .hero-section > .row {
        padding: 0 12px;
    }
}

.hero-card {
    background: rgba(255, 255, 255, 0.1);
    backdrop-filter: blur(10px);
    border-radius: var(--radius-xl);
    padding: 50px 30px;
    box-shadow: var(--shadow-xl);
    border: 1px solid rgba(255, 255, 255, 0.2);
    animation: fadeInUp 0.8s ease-out;
}

@media (max-width: 768px) {
    .hero-card {
        padding: 35px 25px;
        border-radius: var(--radius-lg);
    }
}

@media (max-width: 576px) {
    .hero-card {
        padding: 25px 20px;
    }
}

.hero-content {
    animation: fadeInUp 0.8s ease-out;
}

.hero-title {
    font-size: 2.5rem;
    font-weight: 700;
    color: #fff;
    margin-bottom: 1.5rem;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.2);
    line-height: 1.2;
}

@media (max-width: 768px) {
    .hero-title {
        font-size: 2rem;
    }
}

@media (max-width: 576px) {
    .hero-title {
        font-size: 1.6rem;
    }
}

.hero-subtitle {
    font-size: 1.2rem;
    color: rgba(255, 255, 255, 0.95);
    font-weight: 300;
    line-height: 1.8;
}

@media (max-width: 768px) {
    .hero-subtitle {
        font-size: 1.1rem;
    }
}

@media (max-width: 576px) {
    .hero-subtitle {
        font-size: 1rem;
        line-height: 1.6;
    }
}

.hero-buttons {
    animation: fadeInUp 1s ease-out 0.3s both;
    display: flex;
    justify-content: center;
    gap: 15px;
    flex-wrap: wrap;
}

@media (max-width: 576px) {
    .hero-buttons {
        flex-direction: column;
        align-items: center;
        gap: 12px;
    }
}

.hero-btn {
    padding: 14px 36px;
    font-size: 1.05rem;
    border-radius: 30px;
    transition: all 0.3s ease;
    min-width: 160px;
    font-weight: 600;
    border: none;
    cursor: pointer;
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
}

@media (max-width: 768px) {
    .hero-btn {
        padding: 12px 28px;
        font-size: 1rem;
        min-width: 140px;
    }
}

@media (max-width: 576px) {
    .hero-btn {
        padding: 10px 24px;
        font-size: 0.95rem;
        width: 100%;
        max-width: 300px;
        min-width: auto;
    }
}

.hero-btn:hover {
    transform: translateY(-3px);
    box-shadow: 0 8px 20px rgba(0, 0, 0, 0.3);
}

.hero-btn.btn-primary {
    background: #fff;
    color: var(--primary-color);
}

.hero-btn.btn-outline-light {
    background: transparent;
    color: #fff;
    border: 2px solid rgba(255, 255, 255, 0.8);
}

.hero-btn.btn-outline-light:hover {
    background: rgba(255, 255, 255, 0.1);
    border-color: #fff;
}

.features-section {
    margin-top: 60px;
}

@media (max-width: 768px) {
    .features-section {
        margin-top: 40px;
    }
}

/* 导航卡片样式 */
.navigation-section {
    margin-top: 60px;
}

.nav-card {
    display: block;
    background: white;
    border-radius: var(--radius-xl);
    padding: 30px 25px;
    text-decoration: none;
    color: inherit;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
    transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
    position: relative;
    overflow: hidden;
    height: 100%;
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
}

.nav-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, #667eea 0%, #764ba2 50%, #f093fb 100%);
    transform: scaleX(0);
    transition: transform 0.3s ease;
}

.nav-card:hover::before {
    transform: scaleX(1);
}

.nav-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 15px 40px rgba(102, 126, 234, 0.25);
    color: inherit;
}

.nav-icon {
    width: 70px;
    height: 70px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 28px;
    color: white;
    margin-bottom: 20px;
    transition: all 0.3s ease;
    position: relative;
}

.nav-icon::after {
    content: '';
    position: absolute;
    width: 80px;
    height: 80px;
    border: 2px solid rgba(102, 126, 234, 0.3);
    border-radius: 50%;
    animation: pulse-ring 2s infinite;
}

.nav-card:hover .nav-icon {
    transform: scale(1.1) rotate(5deg);
    box-shadow: 0 8px 25px rgba(102, 126, 234, 0.4);
}

.nav-title {
    font-size: 18px;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 10px;
}

.nav-desc {
    font-size: 14px;
    color: var(--text-secondary);
    margin-bottom: 15px;
    line-height: 1.6;
}

.nav-arrow {
    width: 40px;
    height: 40px;
    background: linear-gradient(135deg, rgba(102, 126, 234, 0.1) 0%, rgba(118, 75, 162, 0.1) 100%);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: #667eea;
    transition: all 0.3s ease;
    margin-top: auto;
}

.nav-card:hover .nav-arrow {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    transform: translateX(5px);
}

@media (max-width: 768px) {
    .navigation-section {
        margin-top: 40px;
    }
    
    .nav-card {
        padding: 25px 20px;
    }
    
    .nav-icon {
        width: 60px;
        height: 60px;
        font-size: 24px;
    }
    
    .nav-icon::after {
        width: 70px;
        height: 70px;
    }
    
    .nav-title {
        font-size: 16px;
    }
    
    .nav-desc {
        font-size: 13px;
    }
}

@media (max-width: 576px) {
    .nav-card {
        padding: 20px 15px;
    }
    
    .nav-icon {
        width: 55px;
        height: 55px;
        font-size: 22px;
        margin-bottom: 15px;
    }
    
    .nav-icon::after {
        width: 65px;
        height: 65px;
    }
    
    .nav-title {
        font-size: 15px;
        margin-bottom: 8px;
    }
    
    .nav-desc {
        font-size: 12px;
        margin-bottom: 12px;
    }
    
    .nav-arrow {
        width: 35px;
        height: 35px;
        font-size: 14px;
    }
}

.feature-card {
    background: var(--bg-white);
    border-radius: var(--radius-lg);
    padding: 35px 25px;
    text-align: center;
    box-shadow: var(--shadow-md);
    transition: all 0.3s ease;
    height: 100%;
    border: 1px solid var(--border-color);
    margin-bottom: 20px;
}

@media (max-width: 768px) {
    .feature-card {
        padding: 30px 20px;
    }
}

@media (max-width: 576px) {
    .feature-card {
        padding: 25px 15px;
    }
}

.feature-card:hover {
    transform: translateY(-10px);
    box-shadow: var(--shadow-lg);
}

.feature-icon {
    width: 80px;
    height: 80px;
    margin: 0 auto 20px;
    background: var(--primary-gradient);
    border-radius: var(--radius-full);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2rem;
    color: #fff;
    transition: all 0.3s ease;
}

@media (max-width: 768px) {
    .feature-icon {
        width: 70px;
        height: 70px;
        font-size: 1.8rem;
        margin-bottom: 15px;
    }
}

@media (max-width: 576px) {
    .feature-icon {
        width: 60px;
        height: 60px;
        font-size: 1.6rem;
    }
}

.feature-card:hover .feature-icon {
    transform: scale(1.1) rotate(5deg);
    box-shadow: 0 8px 20px rgba(102, 126, 234, 0.4);
}

.feature-title {
    font-size: 1.4rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 12px;
    line-height: 1.3;
}

@media (max-width: 768px) {
    .feature-title {
        font-size: 1.3rem;
    }
}

@media (max-width: 576px) {
    .feature-title {
        font-size: 1.2rem;
        margin-bottom: 10px;
    }
}

.feature-description {
    color: var(--text-secondary);
    font-size: 1rem;
    line-height: 1.8;
}

.stats-section {
    margin-top: 60px;
}

@media (max-width: 768px) {
    .stats-section {
        margin-top: 40px;
    }
}

.stats-card {
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-radius: var(--radius-xl);
    padding: 40px 30px;
    box-shadow: var(--shadow-lg);
    border: 1px solid rgba(255, 255, 255, 0.3);
}

@media (max-width: 768px) {
    .stats-card {
        padding: 30px 20px;
        border-radius: var(--radius-lg);
    }
}

@media (max-width: 576px) {
    .stats-card {
        padding: 25px 15px;
    }
}

.section-title {
    font-size: 2rem;
    font-weight: 700;
    color: var(--text-primary);
    text-align: center;
    margin-bottom: 30px;
    line-height: 1.3;
}

@media (max-width: 768px) {
    .section-title {
        font-size: 1.7rem;
        margin-bottom: 25px;
    }
}

@media (max-width: 576px) {
    .section-title {
        font-size: 1.5rem;
        margin-bottom: 20px;
    }
}

.info-section {
    margin-top: 60px;
}

@media (max-width: 768px) {
    .info-section {
        margin-top: 40px;
    }
}

.info-card {
    background: var(--bg-white);
    border-radius: var(--radius-lg);
    padding: 30px 25px;
    display: flex;
    align-items: center;
    gap: 20px;
    box-shadow: var(--shadow-md);
    transition: all 0.3s ease;
    border: 1px solid var(--border-color);
    height: 100%;
    margin-bottom: 20px;
}

@media (max-width: 768px) {
    .info-card {
        flex-direction: column;
        text-align: center;
        padding: 25px 20px;
    }
}

@media (max-width: 576px) {
    .info-card {
        padding: 20px 15px;
    }
}

.info-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-lg);
}

.info-icon {
    width: 80px;
    height: 80px;
    border-radius: var(--radius-full);
    background: var(--primary-gradient);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2rem;
    color: #fff;
    flex-shrink: 0;
    transition: all 0.3s ease;
}

.info-card:hover .info-icon {
    transform: scale(1.1) rotate(5deg);
    box-shadow: 0 8px 20px rgba(102, 126, 234, 0.4);
}

.info-content {
    flex: 1;
}

.info-title {
    font-size: 1.5rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 12px;
}

.info-description {
    color: var(--text-secondary);
    font-size: 1rem;
    line-height: 1.8;
    margin: 0;
}

.stat-card {
    background: var(--bg-white);
    border-radius: var(--radius-lg);
    padding: 30px 25px;
    display: flex;
    align-items: center;
    gap: 20px;
    box-shadow: var(--shadow-md);
    transition: all 0.3s ease;
    border: 1px solid var(--border-color);
    height: 100%;
    margin-bottom: 20px;
}

@media (max-width: 992px) {
    .stat-card {
        flex-direction: column;
        text-align: center;
        padding: 25px 20px;
    }
    
    .stat-icon {
        width: 60px;
        height: 60px;
        font-size: 1.5rem;
    }
    
    .stat-number {
        font-size: 1.8rem;
    }
    
    .stat-label {
        font-size: 0.85rem;
    }
}

@media (max-width: 576px) {
    .stat-card {
        padding: 18px 12px;
    }
    
    .stat-icon {
        width: 50px;
        height: 50px;
        font-size: 1.3rem;
        margin-bottom: 10px;
    }
    
    .stat-number {
        font-size: 1.5rem;
        margin-bottom: 5px;
    }
    
    .stat-label {
        font-size: 0.75rem;
        line-height: 1.2;
    }
}

.stat-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.stat-icon {
    width: 80px;
    height: 80px;
    border-radius: var(--radius-full);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 2rem;
    color: #fff;
    flex-shrink: 0;
}

.stat-primary .stat-icon {
    background: var(--primary-gradient);
}

.stat-success .stat-icon {
    background: var(--secondary-gradient);
}

.stat-info .stat-icon {
    background: var(--info-gradient);
}

.stat-warning .stat-icon {
    background: var(--warning-gradient);
}

.stat-content {
    flex: 1;
}

.stat-number {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 8px;
    line-height: 1.1;
}



.stat-label {
    font-size: 1rem;
    color: var(--text-secondary);
    margin: 0;
    line-height: 1.4;
}



.form-container {
    max-width: 500px;
    margin: 30px auto;
    background: var(--bg-white);
    padding: 35px 30px;
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-lg);
}

@media (max-width: 768px) {
    .form-container {
        margin: 25px auto;
        padding: 30px 25px;
    }
}

@media (max-width: 576px) {
    .form-container {
        max-width: 100%;
        margin: 20px 10px;
        padding: 25px 20px;
        border-radius: var(--radius-md);
    }
}

.form-container h2 {
    text-align: center;
    margin-bottom: 30px;
    color: var(--text-primary);
    font-weight: 700;
}

.form-label {
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 8px;
}

.form-control {
    border: 2px solid var(--border-color);
    border-radius: var(--radius-sm);
    padding: 12px 16px;
    font-size: 1rem;
    transition: all 0.3s ease;
}

.form-control:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

.form-text {
    color: var(--text-muted);
    font-size: 0.9rem;
}

.btn {
    padding: 12px 24px;
    border-radius: var(--radius-sm);
    font-weight: 600;
    transition: all 0.3s ease;
    border: none;
    cursor: pointer;
    display: inline-block;
    text-align: center;
    white-space: nowrap;
}

@media (max-width: 576px) {
    .btn {
        padding: 10px 20px;
        font-size: 0.95rem;
    }
}

.btn:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.btn-primary {
    background: var(--primary-gradient);
    color: #fff;
}

.btn-primary:hover {
    background: var(--primary-gradient);
    box-shadow: 0 5px 15px rgba(102, 126, 234, 0.4);
}

.btn-secondary {
    background: var(--info-gradient);
    color: #fff;
}

.btn-secondary:hover {
    background: var(--info-gradient);
    box-shadow: 0 5px 15px rgba(79, 172, 254, 0.4);
}

.btn-danger {
    background: var(--warning-gradient);
    color: #fff;
}

.btn-danger:hover {
    background: var(--warning-gradient);
    box-shadow: 0 5px 15px rgba(245, 87, 108, 0.4);
}

.btn-success {
    background: var(--secondary-gradient);
    color: #fff;
}

.btn-success:hover {
    background: var(--secondary-gradient);
    box-shadow: 0 5px 15px rgba(17, 153, 142, 0.4);
}

.btn-sm {
    padding: 8px 16px;
    font-size: 0.9rem;
}

@media (max-width: 576px) {
    .btn-sm {
        padding: 6px 12px;
        font-size: 0.85rem;
    }
}

.btn-lg {
    padding: 16px 32px;
    font-size: 1.1rem;
}

@media (max-width: 768px) {
    .btn-lg {
        padding: 14px 28px;
        font-size: 1.05rem;
    }
}

@media (max-width: 576px) {
    .btn-lg {
        padding: 12px 24px;
        font-size: 1rem;
    }
}

.card {
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    transition: all 0.3s ease;
    overflow: hidden;
    height: 100%;
}

.card:hover {
    box-shadow: var(--shadow-md);
}

.card-header {
    background: var(--primary-gradient);
    color: #fff;
    font-weight: 600;
    padding: 18px 24px;
    border: none;
}

.card-body {
    padding: 24px;
}

.card-title {
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 12px;
}

.card-text {
    color: var(--text-secondary);
    margin-bottom: 16px;
}

.video-card {
    margin-bottom: 24px;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    overflow: hidden;
    transition: all 0.3s ease;
    box-shadow: var(--shadow-sm);
    height: 100%;
}

@media (max-width: 576px) {
    .video-card {
        margin-bottom: 20px;
    }
}

.video-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
}

.qr-code-container {
    text-align: center;
    margin: 20px 0;
    padding: 0 10px;
}

.qr-code {
    max-width: 300px;
    width: 100%;
    height: auto;
    margin: 0 auto;
    border: 3px solid var(--primary-color);
    border-radius: var(--radius-md);
    padding: 10px;
    background: #fff;
}

@media (max-width: 768px) {
    .qr-code {
        max-width: 250px;
    }
}

@media (max-width: 576px) {
    .qr-code {
        max-width: 200px;
        border-width: 2px;
    }
}

.alert {
    border-radius: var(--radius-sm);
    padding: 16px 20px;
    margin-bottom: 20px;
    border: none;
    font-weight: 500;
}

.alert-danger {
    background: linear-gradient(135deg, #ff6b6b 0%, #ee5a6f 100%);
    color: #fff;
}

.alert-success {
    background: var(--secondary-gradient);
    color: #fff;
}

.alert-info {
    background: var(--info-gradient);
    color: #fff;
}

.alert-warning {
    background: var(--warning-gradient);
    color: #fff;
}

.error {
    color: #dc3545;
    margin-bottom: 10px;
}

.success {
    color: #28a745;
    margin-bottom: 10px;
}

footer {
    margin-top: 60px;
    padding: 25px 0;
    background: var(--bg-light);
    border-top: 1px solid var(--border-color);
    text-align: center;
}

@media (max-width: 768px) {
    footer {
        margin-top: 40px;
        padding: 20px 0;
    }
}

@media (max-width: 576px) {
    footer {
        margin-top: 30px;
        padding: 15px 0;
    }
}

footer p {
    color: var(--text-muted);
    margin: 0;
}

.video-player {
    width: 100%;
    max-width: 900px;
    margin: 0 auto;
    padding: 0 10px;
}

.video-player video {
    width: 100%;
    height: auto;
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-lg);
}

@media (max-width: 576px) {
    .video-player {
        padding: 0;
    }
    
    .video-player video {
        border-radius: var(--radius-sm);
    }
}

.category-list {
    list-style: none;
    padding: 0;
}

.category-list li {
    background-color: var(--bg-white);
    padding: 16px 20px;
    margin-bottom: 12px;
    border-radius: var(--radius-sm);
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-color);
    transition: all 0.3s ease;
}

.category-list li:hover {
    transform: translateX(5px);
    box-shadow: var(--shadow-md);
}

.admin-content {
    padding: 30px;
    background: var(--bg-light);
    min-height: calc(100vh - 60px);
}

@media (max-width: 992px) {
    .admin-content {
        padding: 25px 20px;
    }
}

@media (max-width: 768px) {
    .admin-content {
        padding: 20px 15px;
    }
}

@media (max-width: 576px) {
    .admin-content {
        padding: 15px 10px;
    }
}

.admin-content h2 {
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 30px;
}

.admin-content .card {
    margin-bottom: 24px;
    height: auto;
}

.admin-content .card-header {
    background: var(--primary-gradient);
    color: #fff;
    font-weight: 600;
}

.admin-content .table {
    margin-bottom: 0;
    width: 100%;
    overflow-x: auto;
    display: block;
}

@media (min-width: 768px) {
    .admin-content .table {
        display: table;
    }
}

@media (max-width: 767px) {
    .admin-content .table thead {
        display: none;
    }
    
    .admin-content .table tbody,
    .admin-content .table tr,
    .admin-content .table td {
        display: block;
        width: 100%;
    }
    
    .admin-content .table tr {
        margin-bottom: 15px;
        border: 1px solid var(--border-color);
        border-radius: var(--radius-sm);
        padding: 10px;
    }
    
    .admin-content .table td {
        text-align: right;
        padding: 8px;
        border: none;
        position: relative;
        padding-left: 50%;
    }
    
    .admin-content .table td:before {
        content: attr(data-label);
        position: absolute;
        left: 10px;
        font-weight: 600;
        text-align: left;
    }
}

.admin-content .table thead th {
    background: var(--bg-light);
    border-bottom: 2px solid var(--border-color);
    font-weight: 600;
    color: var(--text-primary);
    padding: 12px;
    white-space: nowrap;
}

@media (max-width: 992px) {
    .admin-content .table thead th {
        padding: 10px 8px;
        font-size: 0.9rem;
    }
}

.admin-content .table tbody td {
    padding: 12px;
    vertical-align: middle;
    border-bottom: 1px solid var(--border-color);
}

@media (max-width: 992px) {
    .admin-content .table tbody td {
        padding: 10px 8px;
        font-size: 0.9rem;
    }
}

.admin-content .table tbody tr:hover {
    background: rgba(102, 126, 234, 0.05);
    transform: scale(1.01);
    transition: all 0.3s ease;
}

/* 后台表格美化样式 */
.table-dark {
    background: linear-gradient(135deg, #2c3e50 0%, #34495e 100%);
}

.table-dark th {
    border-color: rgba(255, 255, 255, 0.1) !important;
    font-weight: 600;
    text-transform: uppercase;
    font-size: 0.85rem;
    letter-spacing: 0.5px;
}

.table-hover tbody tr {
    transition: all 0.3s ease;
}

.table-striped tbody tr:nth-of-type(odd) {
    background-color: rgba(0, 0, 0, 0.02);
}

/* 卡片头部渐变背景 */
.bg-gradient {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%) !important;
}

.card.shadow-sm {
    box-shadow: 0 0.125rem 0.5rem rgba(0, 0, 0, 0.08) !important;
    border-radius: 12px;
    overflow: hidden;
    transition: all 0.3s ease;
}

.card.shadow-sm:hover {
    box-shadow: 0 0.5rem 1rem rgba(0, 0, 0, 0.15) !important;
    transform: translateY(-2px);
}

.card-header h5, .card-header h6 {
    margin: 0;
}

/* 按钮组优化 */
.btn-group .btn {
    transition: all 0.3s ease;
}

.btn-group .btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.15);
}

/* Badge 优化 */
.badge {
    transition: all 0.3s ease;
}

.badge:hover {
    transform: scale(1.05);
}

/* 表单控件优化 */
.form-control:focus,
.form-select:focus {
    border-color: #667eea;
    box-shadow: 0 0 0 0.25rem rgba(102, 126, 234, 0.25);
}

/* 响应式表格 */
.table-responsive {
    border-radius: 8px;
    overflow: hidden;
}

/* 操作按钮组 */
.btn-group .btn-sm {
    padding: 0.35rem 0.65rem;
    font-size: 0.85rem;
}

.btn-outline-primary:hover,
.btn-outline-danger:hover {
    transform: translateY(-1px);
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

/* 空状态显示 */
.text-center .fa-inbox {
    opacity: 0.3;
    color: #6c757d;
}

/* 筛选区域优化 */
.card-header.bg-light {
    background: linear-gradient(135deg, #f8f9fa 0%, #e9ecef 100%) !important;
    border-bottom: 1px solid #dee2e6;
}

/* 批量操作工具栏 */
.bg-light.rounded {
    background: linear-gradient(135deg, #f8f9fa 0%, #e9ecef 100%) !important;
    border: 1px solid #dee2e6;
}

/* 动画效果 */
@keyframes slideDown {
    from {
        opacity: 0;
        transform: translateY(-10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.alert {
    animation: slideDown 0.3s ease-out;
}

.badge {
    padding: 6px 12px;
    border-radius: 20px;
    font-weight: 600;
    font-size: 0.85rem;
}

.badge-primary {
    background: var(--primary-gradient);
    color: #fff;
}

.badge-secondary {
    background: var(--info-gradient);
    color: #fff;
}

.badge-success {
    background: var(--secondary-gradient);
    color: #fff;
}

.badge-warning {
    background: var(--warning-gradient);
    color: #fff;
}

.badge-danger {
    background: linear-gradient(135deg, #ff6b6b 0%, #ee5a6f 100%);
    color: #fff;
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes fadeIn {
    from {
        opacity: 0;
    }
    to {
        opacity: 1;
    }
}

@keyframes slideInLeft {
    from {
        opacity: 0;
        transform: translateX(-30px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

@keyframes slideInRight {
    from {
        opacity: 0;
        transform: translateX(30px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

@keyframes pulse {
    0%, 100% {
        transform: scale(1);
    }
    50% {
        transform: scale(1.05);
    }
}

@keyframes bounce {
    0%, 20%, 50%, 80%, 100% {
        transform: translateY(0);
    }
    40% {
        transform: translateY(-10px);
    }
    60% {
        transform: translateY(-5px);
    }
}

.animate-fadeInUp {
    animation: fadeInUp 0.6s ease-out;
}

.animate-fadeIn {
    animation: fadeIn 0.6s ease-out;
}

.animate-slideInLeft {
    animation: slideInLeft 0.6s ease-out;
}

.animate-slideInRight {
    animation: slideInRight 0.6s ease-out;
}

.animate-pulse {
    animation: pulse 2s infinite;
}

.animate-bounce {
    animation: bounce 2s infinite;
}







::-webkit-scrollbar {
    width: 10px;
}

::-webkit-scrollbar-track {
    background: var(--bg-light);
}

::-webkit-scrollbar-thumb {
    background: var(--primary-color);
    border-radius: 5px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--secondary-color);
}

::-webkit-input-placeholder {
    color: var(--text-muted);
}

:-moz-placeholder {
    color: var(--text-muted);
}

::-moz-placeholder {
    color: var(--text-muted);
}

:-ms-input-placeholder {
    color: var(--text-muted);
}

input:focus,
textarea:focus,
select:focus {
    outline: none;
}

a {
    text-decoration: none;
    color: inherit;
    transition: all 0.3s ease;
}

a:hover {
    text-decoration: none;
}

button,
.btn,
.nav-btn,
input[type="submit"],
input[type="button"] {
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

button:active,
.btn:active {
    transform: scale(0.98);
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

.text-center {
    text-align: center;
}

.text-muted {
    color: var(--text-muted) !important;
}

.small {
    font-size: 0.875rem;
}

.d-flex {
    display: flex;
}

.align-items-center {
    align-items: center;
}

.justify-content-center {
    justify-content: center;
}

.justify-content-between {
    justify-content: space-between;
}

.gap-2 {
    gap: 8px;
}

.gap-3 {
    gap: 12px;
}

.gap-4 {
    gap: 16px;
}

@media (max-width: 576px) {
    .gap-2 {
        gap: 6px;
    }
    
    .gap-3 {
        gap: 10px;
    }
    
    .gap-4 {
        gap: 12px;
    }
}

.flex-fill {
    flex: 1;
}

.mb-2 {
    margin-bottom: 8px;
}

.mb-3 {
    margin-bottom: 12px;
}

.mb-4 {
    margin-bottom: 16px;
}

.mb-5 {
    margin-bottom: 20px;
}

.mt-2 {
    margin-top: 8px;
}

.mt-3 {
    margin-top: 12px;
}

.mt-4 {
    margin-top: 16px;
}

.mt-5 {
    margin-top: 20px;
}

.py-3 {
    padding-top: 12px;
    padding-bottom: 12px;
}

.py-5 {
    padding-top: 20px;
    padding-bottom: 20px;
}

.p-3 {
    padding: 12px;
}

.bg-light {
    background-color: var(--bg-light) !important;
}

.bg-primary {
    background: var(--primary-gradient) !important;
}

.bg-success {
    background: var(--secondary-gradient) !important;
}

.bg-info {
    background: var(--info-gradient) !important;
}

.bg-warning {
    background: var(--warning-gradient) !important;
}

.bg-danger {
    background: linear-gradient(135deg, #ff6b6b 0%, #ee5a6f 100%) !important;
}

.rounded {
    border-radius: var(--radius-sm);
}

.text-white {
    color: #fff !important;
}

.text-primary {
    color: var(--primary-color) !important;
}

.text-success {
    color: var(--success-color) !important;
}

.text-danger {
    color: var(--warning-color) !important;
}

.w-100 {
    width: 100%;
}

.h-100 {
    height: 100%;
}

.mw-100 {
    max-width: 100%;
}

.display-4 {
    font-size: 3rem;
    font-weight: 700;
    line-height: 1.2;
}

@media (max-width: 768px) {
    .display-4 {
        font-size: 2.5rem;
    }
}

@media (max-width: 576px) {
    .display-4 {
        font-size: 2rem;
    }
}

.fw-bold {
    font-weight: 700;
}

.position-relative {
    position: relative;
}

.position-absolute {
    position: absolute;
}

.table-responsive {
    width: 100%;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
}

.table-responsive > .table {
    margin-bottom: 0;
}

@media (max-width: 767px) {
    .table-responsive {
        border: 1px solid var(--border-color);
        border-radius: var(--radius-sm);
    }
}

.card,
.feature-card,
.info-card,
.stat-card,
.video-card {
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.card:hover,
.feature-card:hover,
.info-card:hover,
.stat-card:hover,
.video-card:hover {
    transform: translateY(-5px);
}

/* 视频质量角标动画 */
@keyframes pulse-glow {
    0%, 100% {
        box-shadow: 0 2px 8px rgba(255,193,7,0.3), 0 0 10px rgba(255,193,7,0.2);
    }
    50% {
        box-shadow: 0 2px 12px rgba(255,193,7,0.5), 0 0 20px rgba(255,193,7,0.4);
    }
}

/* ==================== 后台管理侧边栏样式 ==================== */
.admin-sidebar {
    min-height: 100vh;
    background: linear-gradient(180deg, #2c3e50 0%, #34495e 100%);
    box-shadow: 2px 0 10px rgba(0, 0, 0, 0.1);
    position: sticky;
    top: 0;
    padding: 0 !important;
    max-width: 200px;
}

/* 侧边栏头部 */
.sidebar-header {
    padding: 20px 15px;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
    background: rgba(0, 0, 0, 0.1);
}

.sidebar-brand {
    display: flex;
    align-items: center;
    gap: 8px;
    color: #fff;
    font-size: 1.1rem;
    font-weight: 700;
    margin-bottom: 15px;
    padding-bottom: 12px;
    border-bottom: 2px solid rgba(255, 255, 255, 0.1);
}

.sidebar-brand i {
    font-size: 1.2rem;
    color: #3498db;
}

.sidebar-user {
    display: flex;
    align-items: center;
    gap: 8px;
    color: #ecf0f1;
    padding: 10px 8px;
    background: rgba(255, 255, 255, 0.05);
    border-radius: 8px;
    transition: all 0.3s ease;
}

.sidebar-user:hover {
    background: rgba(255, 255, 255, 0.08);
}

.sidebar-user i {
    font-size: 1.5rem;
    color: #3498db;
}

.sidebar-user span {
    font-weight: 600;
    font-size: 0.85rem;
}

.sidebar-user small {
    font-size: 0.7rem;
    color: #bdc3c7;
    margin-top: 2px;
}

/* 侧边栏导航 */
.sidebar-nav {
    padding: 15px 0;
}

.sidebar-nav .nav-item {
    margin: 0;
    padding: 0 10px;
}

.sidebar-nav .nav-link {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 12px 12px;
    color: #ecf0f1;
    font-size: 0.9rem;
    font-weight: 500;
    border-radius: 8px;
    margin-bottom: 4px;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    position: relative;
    overflow: hidden;
}

.sidebar-nav .nav-link::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    height: 100%;
    width: 4px;
    background: #3498db;
    transform: scaleY(0);
    transition: transform 0.3s ease;
}

.sidebar-nav .nav-link:hover {
    background: rgba(52, 152, 219, 0.15);
    color: #fff;
    transform: translateX(5px);
}

.sidebar-nav .nav-link:hover::before {
    transform: scaleY(1);
}

.sidebar-nav .nav-link.active {
    background: linear-gradient(135deg, #3498db 0%, #2980b9 100%);
    color: #fff;
    box-shadow: 0 4px 15px rgba(52, 152, 219, 0.3);
    transform: translateX(5px);
}

.sidebar-nav .nav-link.active::before {
    transform: scaleY(1);
    background: #fff;
}

.sidebar-nav .nav-link i {
    font-size: 1.1rem;
    width: 20px;
    text-align: center;
    transition: all 0.3s ease;
}

.sidebar-nav .nav-link:hover i,
.sidebar-nav .nav-link.active i {
    transform: scale(1.1);
}

/* 退出登录按钮特殊样式 */
.sidebar-nav .nav-link-logout {
    color: #e74c3c;
    border: 1px solid rgba(231, 76, 60, 0.3);
}

.sidebar-nav .nav-link-logout:hover {
    background: rgba(231, 76, 60, 0.15);
    color: #fff;
    border-color: #e74c3c;
}

.sidebar-nav .nav-link-logout i {
    color: #e74c3c;
}

.sidebar-nav .nav-link-logout:hover i {
    color: #fff;
}

/* 分割线 */
.sidebar-divider {
    height: 1px;
    background: rgba(255, 255, 255, 0.1);
    margin: 15px 15px;
}

/* 后台内容区域 */
.admin-content {
    padding: 30px;
    background: #f8f9fa;
    min-height: calc(100vh - 60px);
}

@media (max-width: 768px) {
    .admin-sidebar {
        position: relative;
        min-height: auto;
    }
    
    .sidebar-brand span {
        font-size: 1.1rem;
    }
    
    .admin-content {
        padding: 20px 15px;
    }
}

@media (max-width: 576px) {
    .sidebar-header {
        padding: 20px 15px;
    }
    
    .sidebar-brand {
        font-size: 1.1rem;
    }
    
    .sidebar-user {
        font-size: 0.9rem;
    }
    
    .sidebar-nav .nav-link {
        padding: 12px 15px;
        font-size: 0.9rem;
    }
}

/* 后台视频卡片视图样式 */
.video-card {
    background: white;
    border-radius: 16px;
    overflow: hidden;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.06);
    transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
    height: 100%;
    display: flex;
    flex-direction: column;
    position: relative;
    border: 1px solid rgba(0, 0, 0, 0.04);
}

.video-card:hover {
    transform: translateY(-8px) scale(1.02);
    box-shadow: 0 12px 28px rgba(102, 126, 234, 0.25), 0 0 0 1px rgba(102, 126, 234, 0.1);
}

.video-card.expired {
    opacity: 0.88;
    border: 2px solid #ffc107;
    background: linear-gradient(to bottom, rgba(255, 193, 7, 0.02) 0%, white 100%);
}

.video-card.expired:hover {
    box-shadow: 0 12px 28px rgba(255, 193, 7, 0.3);
}

.card-checkbox {
    position: absolute;
    top: 12px;
    left: 12px;
    z-index: 10;
    background: rgba(255, 255, 255, 0.95);
    padding: 6px 10px;
    border-radius: 8px;
    box-shadow: 0 2px 12px rgba(0, 0, 0, 0.15);
    backdrop-filter: blur(10px);
    transition: all 0.3s ease;
}

.card-checkbox:hover {
    background: rgba(255, 255, 255, 1);
    transform: scale(1.05);
}

.card-checkbox input[type="checkbox"] {
    width: 20px;
    height: 20px;
    cursor: pointer;
    accent-color: #667eea;
}

.video-thumbnail {
    position: relative;
    width: 100%;
    height: 200px;
    overflow: hidden;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    display: flex;
    align-items: center;
    justify-content: center;
}

.video-thumbnail::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(to bottom, rgba(0,0,0,0) 0%, rgba(0,0,0,0.3) 100%);
    opacity: 0;
    transition: opacity 0.3s ease;
    pointer-events: none;
}

.video-card:hover .video-thumbnail::before {
    opacity: 1;
}

.video-thumbnail img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}

.video-card:hover .video-thumbnail img {
    transform: scale(1.08);
}

.no-thumbnail {
    color: rgba(255, 255, 255, 0.9);
    display: flex;
    align-items: center;
    justify-content: center;
    width: 100%;
    height: 100%;
    animation: float 3s ease-in-out infinite;
}

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

.video-badge {
    position: absolute;
    top: 12px;
    right: 12px;
    z-index: 5;
    animation: fadeInSlide 0.5s ease-out;
}

.video-badge .badge {
    backdrop-filter: blur(10px);
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.2);
    border: 1px solid rgba(255, 255, 255, 0.2);
    font-weight: 600;
}

@keyframes fadeInSlide {
    from {
        opacity: 0;
        transform: translateX(10px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

.video-card-body {
    padding: 18px;
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 2px;
}

.video-card-title {
    font-size: 1.05rem;
    font-weight: 700;
    color: #2c3e50;
    margin-bottom: 14px;
    line-height: 1.5;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
    text-overflow: ellipsis;
    min-height: 3.0em;
    transition: color 0.3s ease;
}

.video-card:hover .video-card-title {
    color: #667eea;
}

.video-card-meta {
    display: flex;
    flex-direction: column;
    gap: 10px;
    margin-bottom: 14px;
    font-size: 0.875rem;
    color: #5a6c7d;
}

.meta-item {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 6px 10px;
    background: linear-gradient(135deg, rgba(102, 126, 234, 0.04) 0%, rgba(118, 75, 162, 0.04) 100%);
    border-radius: 8px;
    transition: all 0.3s ease;
}

.meta-item:hover {
    background: linear-gradient(135deg, rgba(102, 126, 234, 0.08) 0%, rgba(118, 75, 162, 0.08) 100%);
    transform: translateX(3px);
}

.meta-item i {
    color: #667eea;
    font-size: 0.9rem;
    min-width: 16px;
    text-align: center;
}

.meta-item .badge {
    font-size: 0.8rem;
    padding: 4px 10px;
    border-radius: 6px;
    font-weight: 600;
}

.quality-mark-section {
    margin: 12px 0;
    padding: 10px;
    background: rgba(102, 126, 234, 0.04);
    border-radius: 8px;
    border: 1px dashed rgba(102, 126, 234, 0.2);
}

.quality-mark-section .form-select {
    font-size: 0.875rem;
    padding: 6px 10px;
    border-radius: 8px;
    border: 2px solid rgba(102, 126, 234, 0.2);
    transition: all 0.3s ease;
    font-weight: 600;
}

.quality-mark-section .form-select:hover {
    border-color: #667eea;
    background: rgba(102, 126, 234, 0.05);
}

.quality-mark-section .form-select:focus {
    border-color: #667eea;
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

.video-card-footer {
    margin-top: auto;
    padding-top: 14px;
    border-top: 2px solid rgba(102, 126, 234, 0.08);
}

.video-card-footer .btn-group {
    display: flex;
    gap: 8px;
}

.video-card-footer .btn {
    flex: 1;
    font-size: 0.875rem;
    padding: 8px 12px;
    border-radius: 8px;
    font-weight: 600;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    border: 2px solid currentColor;
}

.video-card-footer .btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
}

.video-card-footer .btn-outline-primary {
    position: relative;
    overflow: hidden;
}

.video-card-footer .btn-outline-primary:hover {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    border-color: transparent;
    color: white;
}

.video-card-footer .btn-outline-danger:hover {
    background: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    border-color: transparent;
    color: white;
}

.video-card-time {
    margin-top: 12px;
    padding-top: 12px;
    border-top: 2px solid rgba(102, 126, 234, 0.08);
    font-size: 0.8rem;
    color: #95a5a6;
    text-align: center;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 6px;
    font-weight: 500;
}

.video-card-time i {
    color: #667eea;
    font-size: 0.85rem;
}

/* 视图切换按钮样式 */
.btn-group .btn.active {
    background: linear-gradient(135deg, rgba(255, 255, 255, 0.95) 0%, rgba(255, 255, 255, 1) 100%) !important;
    color: #667eea !important;
    border-color: rgba(255, 255, 255, 0.5) !important;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.15);
    transform: scale(1.05);
}

.btn-group .btn {
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.btn-group .btn:hover {
    transform: scale(1.05);
}

/* 响应式调整 */
@media (max-width: 768px) {
    .video-thumbnail {
        height: 180px;
    }
    
    .video-card-body {
        padding: 16px;
    }
    
    .video-card-title {
        font-size: 1rem;
    }
    
    .video-card-meta {
        font-size: 0.85rem;
        gap: 8px;
    }
    
    .meta-item {
        padding: 5px 8px;
    }
}

@media (max-width: 576px) {
    .video-thumbnail {
        height: 160px;
    }
    
    .video-card-body {
        padding: 14px;
    }
    
    .video-card-title {
        font-size: 0.95rem;
        margin-bottom: 12px;
    }
    
    .video-card-meta {
        font-size: 0.8rem;
        gap: 8px;
    }
    
    .meta-item {
        padding: 4px 8px;
    }
    
    .video-card-footer .btn {
        font-size: 0.8rem;
        padding: 6px 10px;
    }
    
    .card-checkbox {
        padding: 5px 8px;
    }
    
    .card-checkbox input[type="checkbox"] {
        width: 18px;
        height: 18px;
    }
}

/* 卡片加载动画 */
@keyframes cardFadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.video-card {
    animation: cardFadeIn 0.5s ease-out;
}

/* 不同列数的延迟动画 */
.col-lg-3:nth-child(1) .video-card { animation-delay: 0.05s; }
.col-lg-3:nth-child(2) .video-card { animation-delay: 0.1s; }
.col-lg-3:nth-child(3) .video-card { animation-delay: 0.15s; }
.col-lg-3:nth-child(4) .video-card { animation-delay: 0.2s; }
.col-lg-3:nth-child(5) .video-card { animation-delay: 0.05s; }
.col-lg-3:nth-child(6) .video-card { animation-delay: 0.1s; }
.col-lg-3:nth-child(7) .video-card { animation-delay: 0.15s; }
.col-lg-3:nth-child(8) .video-card { animation-delay: 0.2s; }