:root {
    --primary-blue: #2563eb;
    --primary-dark: #1e40af;
    --accent-cyan: #06b6d4;
    --accent-purple: #8b5cf6;
    --bg-light: #f8fafc;
    --bg-white: #ffffff;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --border-color: #e2e8f0;
    --gradient-primary: linear-gradient(135deg, #2563eb 0%, #8b5cf6 100%);
    --gradient-accent: linear-gradient(135deg, #06b6d4 0%, #3b82f6 100%);
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    --font-primary: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Microsoft YaHei', sans-serif;
}

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

body {
    font-family: var(--font-primary);
    line-height: 1.6;
    color: var(--text-primary);
    background: var(--bg-light);
    overflow-x: hidden;
    position: relative;
}

/* 背景动画效果 */
.animated-bg {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: 
        radial-gradient(circle at 20% 20%, rgba(37, 99, 235, 0.05) 0%, transparent 50%),
        radial-gradient(circle at 80% 30%, rgba(139, 92, 246, 0.04) 0%, transparent 60%),
        radial-gradient(circle at 50% 80%, rgba(6, 182, 212, 0.03) 0%, transparent 70%);
    pointer-events: none;
    z-index: 1;
    animation: bgFloat 20s ease-in-out infinite;
}

@keyframes bgFloat {
    0%, 100% { opacity: 0.6; transform: translateY(0) scale(1); }
    50% { opacity: 1; transform: translateY(-20px) scale(1.02); }
}

.particles-bg {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: 2;
    background: 
        radial-gradient(circle at 25% 25%, rgba(6, 182, 212, 0.08) 0%, transparent 50%),
        radial-gradient(circle at 75% 75%, rgba(139, 92, 246, 0.06) 0%, transparent 60%);
    animation: particlesFloat 18s ease-in-out infinite;
}

@keyframes particlesFloat {
    0%, 100% { transform: translate(0, 0) scale(1); }
    50% { transform: translate(-15px, -20px) scale(1.03); }
}

.container-modern {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

/* 导航栏 */
.modern-navbar {
    position: fixed;
    top: 0;
    width: 100%;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border-color);
    z-index: 1000;
    transition: var(--transition);
    box-shadow: var(--shadow-sm);
}

.modern-navbar .container-modern {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 2rem;
}

.navbar-brand {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.logo-icon {
    width: 40px;
    height: 40px;
    background: var(--gradient-primary);
    border-radius: 10px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    color: white;
    font-weight: bold;
}

.navbar-brand h1 {
    font-size: 1.5rem;
    font-weight: 700;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.navbar-brand a {
    text-decoration: none;
    color: inherit;
}

.modern-navigation {
    display: flex;
    gap: 2rem;
    align-items: center;
}

.nav-item {
    text-decoration: none;
    color: var(--text-secondary);
    font-weight: 500;
    font-size: 0.95rem;
    transition: var(--transition);
    position: relative;
    padding: 0.5rem 0;
}

.nav-item:hover,
.nav-item.active {
    color: var(--primary-blue);
}

.nav-item.active::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 2px;
    background: var(--gradient-primary);
    border-radius: 2px;
}

.navbar-actions {
    display: flex;
    gap: 1rem;
}

.action-btn {
    padding: 0.6rem 1.5rem;
    border: none;
    border-radius: 8px;
    font-weight: 500;
    font-size: 0.9rem;
    cursor: pointer;
    transition: var(--transition);
}

.action-btn.login {
    background: transparent;
    color: var(--primary-blue);
    border: 1px solid var(--border-color);
}

.action-btn.login:hover {
    background: var(--bg-light);
    border-color: var(--primary-blue);
}

.action-btn.register {
    background: var(--gradient-primary);
    color: white;
    box-shadow: var(--shadow-md);
}

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

/* 主内容区域 */
.modern-main {
    margin-top: 80px;
    position: relative;
    z-index: 10;
}

/* Hero区域 */
.hero-modern {
    padding: 6rem 0 4rem;
    background: linear-gradient(135deg, #ffffff 0%, #f8fafc 100%);
    position: relative;
    overflow: hidden;
}

.hero-background {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    opacity: 0.5;
}

.modern-particles {
    position: absolute;
    width: 100%;
    height: 100%;
    background: 
        radial-gradient(circle at 30% 40%, rgba(37, 99, 235, 0.1) 0%, transparent 50%),
        radial-gradient(circle at 70% 60%, rgba(139, 92, 246, 0.08) 0%, transparent 50%);
    animation: particlesMove 15s ease-in-out infinite;
}

@keyframes particlesMove {
    0%, 100% { transform: translate(0, 0); }
    50% { transform: translate(20px, -20px); }
}

.hero-content {
    text-align: center;
    max-width: 800px;
    margin: 0 auto;
}

.hero-title {
    font-size: 3.5rem;
    font-weight: 800;
    margin-bottom: 1.5rem;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    line-height: 1.2;
}

.hero-subtitle {
    font-size: 1.25rem;
    color: var(--text-secondary);
    margin-bottom: 2.5rem;
}

.search-modern {
    display: flex;
    max-width: 600px;
    margin: 0 auto 3rem;
    background: white;
    border-radius: 12px;
    box-shadow: var(--shadow-lg);
    padding: 0.5rem;
    border: 1px solid var(--border-color);
}

.modern-search-input {
    flex: 1;
    border: none;
    padding: 1rem 1.5rem;
    font-size: 1rem;
    outline: none;
    background: transparent;
}

.search-btn {
    padding: 1rem 2rem;
    background: var(--gradient-primary);
    color: white;
    border: none;
    border-radius: 8px;
    cursor: pointer;
    font-size: 1.2rem;
    transition: var(--transition);
}

.search-btn:hover {
    transform: scale(1.05);
    box-shadow: var(--shadow-md);
}

.hero-stats {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 2rem;
    margin-top: 3rem;
}

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

.stat-number {
    display: block;
    font-size: 2.5rem;
    font-weight: 700;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 0.5rem;
}

.stat-label {
    display: block;
    color: var(--text-secondary);
    font-size: 0.95rem;
}

/* 卡片样式 */
.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    text-align: center;
    margin-bottom: 3rem;
    color: var(--text-primary);
}

.section-subtitle {
    text-align: center;
    color: var(--text-secondary);
    font-size: 1.1rem;
    margin-bottom: 3rem;
}

.card-modern {
    background: white;
    border-radius: 16px;
    padding: 2rem;
    box-shadow: var(--shadow-md);
    border: 1px solid var(--border-color);
    transition: var(--transition);
}

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

/* 视频卡片 */
.video-card {
    background: white;
    border-radius: 16px;
    overflow: hidden;
    box-shadow: var(--shadow-md);
    border: 1px solid var(--border-color);
    transition: var(--transition);
}

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

.video-thumbnail {
    position: relative;
    width: 100%;
    padding-top: 56.25%;
    background: var(--bg-light);
    overflow: hidden;
}

.video-thumbnail img {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: var(--transition);
}

.video-card:hover .video-thumbnail img {
    transform: scale(1.05);
}

.play-overlay {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 60px;
    height: 60px;
    background: rgba(255, 255, 255, 0.9);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    cursor: pointer;
    transition: var(--transition);
    z-index: 10;
}

.play-overlay:hover {
    background: white;
    transform: translate(-50%, -50%) scale(1.1);
}

.video-duration {
    position: absolute;
    bottom: 10px;
    right: 10px;
    background: rgba(0, 0, 0, 0.7);
    color: white;
    padding: 0.3rem 0.8rem;
    border-radius: 6px;
    font-size: 0.85rem;
}

.video-info {
    padding: 1.5rem;
}

.video-title {
    font-size: 1.25rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
    color: var(--text-primary);
    line-height: 1.4;
}

.video-desc {
    color: var(--text-secondary);
    font-size: 0.95rem;
    margin-bottom: 1rem;
    line-height: 1.6;
}

.video-meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1rem;
    padding-top: 1rem;
    border-top: 1px solid var(--border-color);
}

.creator-info {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.creator-info img {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    object-fit: cover;
}

.creator-name {
    font-weight: 500;
    color: var(--text-primary);
    font-size: 0.9rem;
}

.video-stats {
    display: flex;
    gap: 1rem;
    font-size: 0.85rem;
    color: var(--text-secondary);
}

.video-tags {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
}

.tag {
    padding: 0.3rem 0.8rem;
    background: var(--bg-light);
    border: 1px solid var(--border-color);
    border-radius: 6px;
    font-size: 0.8rem;
    color: var(--text-secondary);
}

/* 网格布局 */
.videos-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 2rem;
    margin-bottom: 4rem;
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin-bottom: 4rem;
}

.feature-card {
    background: white;
    border-radius: 16px;
    padding: 2.5rem;
    box-shadow: var(--shadow-md);
    border: 1px solid var(--border-color);
    transition: var(--transition);
    text-align: center;
}

.feature-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-xl);
    border-color: var(--primary-blue);
}

.feature-icon {
    font-size: 3rem;
    margin-bottom: 1.5rem;
}

.feature-title {
    font-size: 1.5rem;
    font-weight: 600;
    margin-bottom: 1rem;
    color: var(--text-primary);
}

.feature-desc {
    color: var(--text-secondary);
    line-height: 1.7;
    margin-bottom: 1rem;
}

.feature-highlight {
    display: inline-block;
    padding: 0.4rem 1rem;
    background: var(--gradient-primary);
    color: white;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 500;
    margin-top: 1rem;
}

/* 页脚 */
.modern-footer {
    background: var(--text-primary);
    color: white;
    padding: 4rem 0 2rem;
    margin-top: 6rem;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 3rem;
    margin-bottom: 3rem;
}

.footer-brand h5 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    background: var(--gradient-accent);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.footer-description {
    color: rgba(255, 255, 255, 0.7);
    line-height: 1.7;
    margin-top: 1rem;
}

.footer-section h6 {
    font-size: 1.1rem;
    margin-bottom: 1.5rem;
    color: white;
}

.footer-links {
    list-style: none;
}

.footer-links li {
    margin-bottom: 0.75rem;
}

.footer-links a {
    color: rgba(255, 255, 255, 0.7);
    text-decoration: none;
    transition: var(--transition);
}

.footer-links a:hover {
    color: white;
    padding-left: 5px;
}

.footer-bottom {
    text-align: center;
    padding-top: 2rem;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    color: rgba(255, 255, 255, 0.6);
    font-size: 0.9rem;
}

/* 页面标题 */
.page-header {
    padding: 4rem 0 3rem;
    background: linear-gradient(135deg, #ffffff 0%, #f8fafc 100%);
    text-align: center;
    border-bottom: 1px solid var(--border-color);
}

.page-title {
    font-size: 3rem;
    font-weight: 800;
    margin-bottom: 1rem;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.page-subtitle {
    font-size: 1.2rem;
    color: var(--text-secondary);
}

/* 响应式设计 */
@media (max-width: 768px) {
    .modern-navigation {
        display: none;
    }
    
    .hero-title {
        font-size: 2.5rem;
    }
    
    .videos-grid {
        grid-template-columns: 1fr;
    }
    
    .features-grid {
        grid-template-columns: 1fr;
    }
}

/* 按钮样式 */
.btn-modern {
    padding: 0.75rem 2rem;
    border: none;
    border-radius: 8px;
    font-weight: 500;
    font-size: 1rem;
    cursor: pointer;
    transition: var(--transition);
    background: var(--gradient-primary);
    color: white;
    box-shadow: var(--shadow-md);
}

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

/* 表单样式 */
.form-modern {
    background: white;
    padding: 2.5rem;
    border-radius: 16px;
    box-shadow: var(--shadow-lg);
    border: 1px solid var(--border-color);
}

.form-group {
    margin-bottom: 1.5rem;
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 500;
    color: var(--text-primary);
}

.form-group input,
.form-group textarea,
.form-group select {
    width: 100%;
    padding: 0.75rem 1rem;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    font-size: 1rem;
    transition: var(--transition);
    font-family: inherit;
}

.form-group input:focus,
.form-group textarea:focus,
.form-group select:focus {
    outline: none;
    border-color: var(--primary-blue);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

/* 工具提示和徽章 */
.badge {
    display: inline-block;
    padding: 0.25rem 0.75rem;
    background: var(--gradient-primary);
    color: white;
    border-radius: 12px;
    font-size: 0.75rem;
    font-weight: 500;
}

/* 动画类 */
.fade-in {
    opacity: 0;
    transform: translateY(20px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in.visible {
    opacity: 1;
    transform: translateY(0);
}