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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
    line-height: 1.6;
    color: #333;
    background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
    min-height: 100vh;
}

.site-wrapper {
    max-width: 1400px;
    margin: 0 auto;
    background: #fff;
    box-shadow: 0 0 40px rgba(0,0,0,0.1);
    animation: fadeIn 0.6s ease-in;
}

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

.site-header {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    color: white;
    padding: 30px 40px;
    box-shadow: 0 4px 20px rgba(102, 126, 234, 0.3);
    position: relative;
    overflow: hidden;
}

.site-header::before {
    content: '';
    position: absolute;
    top: -50%;
    right: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, rgba(255,255,255,0.1) 0%, transparent 70%);
    animation: pulse 15s ease-in-out infinite;
}

@keyframes pulse {
    0%, 100% {
        transform: scale(1);
        opacity: 0.5;
    }
    50% {
        transform: scale(1.1);
        opacity: 0.8;
    }
}

.header-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    position: relative;
    z-index: 1;
}

.logo-area h1 {
    font-size: 32px;
    margin-bottom: 5px;
    font-weight: 700;
    text-shadow: 2px 2px 4px rgba(0,0,0,0.2);
}

.logo-area h1 a {
    color: white;
    text-decoration: none;
    transition: all 0.3s ease;
}

.logo-area h1 a:hover {
    text-shadow: 0 0 20px rgba(255,255,255,0.8);
    transform: scale(1.05);
    display: inline-block;
}

.site-slogan {
    font-size: 14px;
    opacity: 0.9;
    font-style: italic;
}

.user-panel {
    display: flex;
    gap: 15px;
}

.btn-login, .btn-register {
    padding: 10px 25px;
    border-radius: 25px;
    text-decoration: none;
    font-weight: 600;
    transition: all 0.3s ease;
    display: inline-block;
}

.btn-login {
    background: rgba(255,255,255,0.2);
    color: white;
    border: 2px solid white;
}

.btn-login:hover {
    background: white;
    color: #667eea;
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(0,0,0,0.2);
}

.btn-register {
    background: white;
    color: #667eea;
    border: 2px solid white;
}

.btn-register:hover {
    background: #667eea;
    color: white;
    border-color: white;
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(0,0,0,0.2);
}

.main-navigation {
    background: #fff;
    border-bottom: 3px solid #f0f0f0;
    box-shadow: 0 2px 10px rgba(0,0,0,0.05);
    position: sticky;
    top: 0;
    z-index: 100;
}

.nav-container {
    padding: 0 40px;
}

.nav-list {
    list-style: none;
    display: flex;
    gap: 5px;
}

.nav-list li {
    position: relative;
}

.nav-list a {
    display: block;
    padding: 18px 20px;
    color: #555;
    text-decoration: none;
    font-weight: 500;
    transition: all 0.3s ease;
    position: relative;
}

.nav-list a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    width: 0;
    height: 3px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    transition: all 0.3s ease;
    transform: translateX(-50%);
}

.nav-list a:hover,
.nav-list a.active {
    color: #667eea;
    background: rgba(102, 126, 234, 0.05);
}

.nav-list a:hover::after,
.nav-list a.active::after {
    width: 80%;
}

.main-content {
    padding: 40px;
}

.hero-banner {
    background: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    color: white;
    padding: 60px 50px;
    border-radius: 20px;
    margin-bottom: 50px;
    box-shadow: 0 10px 40px rgba(245, 87, 108, 0.3);
    position: relative;
    overflow: hidden;
    animation: slideInDown 0.8s ease-out;
}

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

.hero-banner::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, rgba(255,255,255,0.1) 0%, transparent 70%);
    animation: rotate 20s linear infinite;
}

@keyframes rotate {
    from {
        transform: rotate(0deg);
    }
    to {
        transform: rotate(360deg);
    }
}

.banner-content {
    position: relative;
    z-index: 1;
}

.banner-content h2 {
    font-size: 36px;
    margin-bottom: 20px;
    font-weight: 700;
    text-shadow: 2px 2px 4px rgba(0,0,0,0.2);
}

.banner-content p {
    font-size: 16px;
    line-height: 1.8;
    opacity: 0.95;
}

.section-header {
    margin-bottom: 35px;
    text-align: center;
}

.section-header h3 {
    font-size: 32px;
    color: #2c3e50;
    margin-bottom: 10px;
    font-weight: 700;
    position: relative;
    display: inline-block;
}

.section-header h3::after {
    content: '';
    position: absolute;
    bottom: -10px;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 4px;
    background: linear-gradient(90deg, #667eea, #764ba2);
    border-radius: 2px;
}

.section-header p {
    color: #7f8c8d;
    font-size: 16px;
}

.featured-videos {
    margin-bottom: 60px;
}

.video-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(380px, 1fr));
    gap: 30px;
}

.video-card {
    background: white;
    border-radius: 15px;
    overflow: hidden;
    box-shadow: 0 5px 20px rgba(0,0,0,0.08);
    transition: all 0.3s ease;
    animation: fadeInUp 0.6s ease-out;
    animation-fill-mode: both;
}

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

.video-card:nth-child(1) { animation-delay: 0.1s; }
.video-card:nth-child(2) { animation-delay: 0.2s; }
.video-card:nth-child(3) { animation-delay: 0.3s; }
.video-card:nth-child(4) { animation-delay: 0.4s; }
.video-card:nth-child(5) { animation-delay: 0.5s; }
.video-card:nth-child(6) { animation-delay: 0.6s; }

.video-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 15px 40px rgba(0,0,0,0.15);
}

.video-thumbnail {
    position: relative;
    overflow: hidden;
    height: 220px;
}

.video-thumbnail img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform 0.5s ease;
}

.video-card:hover .video-thumbnail img {
    transform: scale(1.1);
}

.duration {
    position: absolute;
    bottom: 10px;
    right: 10px;
    background: rgba(0,0,0,0.8);
    color: white;
    padding: 5px 10px;
    border-radius: 5px;
    font-size: 13px;
    font-weight: 600;
}

.video-info {
    padding: 20px;
}

.video-info h4 {
    font-size: 18px;
    margin-bottom: 10px;
    line-height: 1.4;
}

.video-info h4 a {
    color: #2c3e50;
    text-decoration: none;
    transition: color 0.3s ease;
}

.video-info h4 a:hover {
    color: #667eea;
}

.video-desc {
    font-size: 14px;
    color: #7f8c8d;
    margin-bottom: 15px;
    line-height: 1.6;
}

.video-stats {
    display: flex;
    flex-wrap: wrap;
    gap: 15px;
    font-size: 13px;
    color: #95a5a6;
}

.video-stats span {
    display: flex;
    align-items: center;
    gap: 5px;
}

.community-topics {
    margin-bottom: 60px;
}

.topic-container {
    display: flex;
    flex-direction: column;
    gap: 25px;
}

.topic-card {
    display: flex;
    gap: 20px;
    background: white;
    padding: 25px;
    border-radius: 15px;
    box-shadow: 0 5px 20px rgba(0,0,0,0.08);
    transition: all 0.3s ease;
    animation: slideInLeft 0.6s ease-out;
    animation-fill-mode: both;
}

@keyframes slideInLeft {
    from {
        opacity: 0;
        transform: translateX(-50px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

.topic-card:nth-child(1) { animation-delay: 0.1s; }
.topic-card:nth-child(2) { animation-delay: 0.2s; }
.topic-card:nth-child(3) { animation-delay: 0.3s; }
.topic-card:nth-child(4) { animation-delay: 0.4s; }
.topic-card:nth-child(5) { animation-delay: 0.5s; }

.topic-card:hover {
    transform: translateX(10px);
    box-shadow: 0 10px 30px rgba(0,0,0,0.12);
}

.topic-icon {
    flex-shrink: 0;
}

.topic-icon img {
    width: 80px;
    height: 80px;
    border-radius: 12px;
    object-fit: cover;
}

.topic-content {
    flex: 1;
}

.topic-content h4 {
    font-size: 18px;
    margin-bottom: 10px;
}

.topic-content h4 a {
    color: #2c3e50;
    text-decoration: none;
    transition: color 0.3s ease;
}

.topic-content h4 a:hover {
    color: #667eea;
}

.topic-intro {
    font-size: 14px;
    color: #7f8c8d;
    line-height: 1.6;
    margin-bottom: 12px;
}

.topic-meta {
    display: flex;
    gap: 20px;
    font-size: 13px;
    color: #95a5a6;
}

.site-footer {
    background: #2c3e50;
    color: white;
    padding: 40px;
    margin-top: 60px;
}

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

.footer-nav {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 25px;
    margin-bottom: 25px;
    padding-bottom: 25px;
    border-bottom: 1px solid rgba(255,255,255,0.1);
}

.footer-nav a {
    color: rgba(255,255,255,0.8);
    text-decoration: none;
    transition: all 0.3s ease;
    font-size: 14px;
}

.footer-nav a:hover {
    color: white;
    transform: translateY(-2px);
}

.footer-info {
    font-size: 14px;
    line-height: 1.8;
    color: rgba(255,255,255,0.7);
}

.footer-info p {
    margin: 5px 0;
}

@media (max-width: 768px) {
    .site-wrapper {
        margin: 0;
    }

    .site-header {
        padding: 20px;
    }

    .header-container {
        flex-direction: column;
        gap: 15px;
    }

    .logo-area h1 {
        font-size: 24px;
    }

    .nav-container {
        padding: 0 20px;
    }

    .nav-list {
        flex-wrap: wrap;
        justify-content: center;
    }

    .nav-list a {
        padding: 12px 15px;
        font-size: 14px;
    }

    .main-content {
        padding: 20px;
    }

    .hero-banner {
        padding: 40px 25px;
    }

    .banner-content h2 {
        font-size: 26px;
    }

    .video-grid {
        grid-template-columns: 1fr;
        gap: 20px;
    }

    .topic-card {
        flex-direction: column;
    }

    .footer-nav {
        flex-direction: column;
        gap: 15px;
    }
}