/* 基础样式重置 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

/* 主体样式 */
body {
    font-family: 'Noto Sans SC', 'Roboto', sans-serif;
    background-color: #FDF6E3;
    color: #2C3E50;
    line-height: 1.6;
    overflow-x: hidden;
}

/* 容器 */
.container {
    width: 100%;
    min-height: 1800px;
    margin: 0;
    padding: 40px;
    background: linear-gradient(135deg, #FDF6E3 0%, #F5E6D3 100%);
    position: relative;
    overflow: visible;
}

/* 装饰性背景元素 */
.container::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: 
        radial-gradient(circle at 20% 30%, rgba(255, 193, 7, 0.1) 0%, transparent 50%),
        radial-gradient(circle at 80% 70%, rgba(52, 152, 219, 0.08) 0%, transparent 50%),
        radial-gradient(circle at 60% 20%, rgba(231, 76, 60, 0.06) 0%, transparent 50%);
    pointer-events: none;
    z-index: 0;
}

/* 头部区域 */
.hero-section {
    position: relative;
    z-index: 1;
    text-align: center;
    margin-bottom: 60px;
    padding: 40px 0;
}

.title-decoration {
    width: 120px;
    height: 4px;
    background: linear-gradient(90deg, #FF6B6B, #4ECDC4, #45B7D1);
    margin: 0 auto 30px;
    border-radius: 2px;
}

.main-title {
    font-size: 72px;
    font-weight: 900;
    color: #2C3E50;
    margin-bottom: 20px;
    text-shadow: 2px 2px 4px rgba(0,0,0,0.1);
    letter-spacing: -2px;
}

.subtitle {
    font-size: 24px;
    font-weight: 300;
    color: #7F8C8D;
    font-family: 'Roboto', sans-serif;
    margin-bottom: 40px;
    letter-spacing: 1px;
}

.intro-text {
    max-width: 800px;
    margin: 0 auto;
    text-align: left;
    background: rgba(255, 255, 255, 0.6);
    padding: 30px;
    border-radius: 15px;
    border-left: 5px solid #3498DB;
    box-shadow: 0 10px 30px rgba(0,0,0,0.1);
}

.intro-main {
    font-size: 18px;
    font-weight: 700;
    color: #2C3E50;
    margin-bottom: 15px;
    text-align: center;
}

.intro-sub {
    font-size: 16px;
    color: #5D6D7E;
    margin-bottom: 15px;
}

.intro-action {
    font-size: 16px;
    font-weight: 600;
    color: #E74C3C;
    background: linear-gradient(90deg, #E74C3C, #F39C12);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    text-align: center;
}

/* 分类导航 */
.category-nav {
    display: flex;
    justify-content: space-between;
    margin-bottom: 50px;
    background: rgba(255, 255, 255, 0.8);
    padding: 20px;
    border-radius: 20px;
    box-shadow: 0 8px 25px rgba(0,0,0,0.1);
    position: relative;
    z-index: 1;
}

.nav-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 15px 20px;
    border-radius: 12px;
    cursor: pointer;
    transition: all 0.3s ease;
    background: linear-gradient(135deg, transparent, rgba(52, 152, 219, 0.05));
}

.nav-item:hover {
    background: linear-gradient(135deg, rgba(52, 152, 219, 0.1), rgba(52, 152, 219, 0.2));
    transform: translateY(-3px);
    box-shadow: 0 8px 20px rgba(52, 152, 219, 0.2);
}

.nav-item i {
    font-size: 24px;
    color: #3498DB;
    margin-bottom: 8px;
    transition: all 0.3s ease;
}

.nav-item:hover i {
    transform: scale(1.2);
    color: #2980B9;
}

.nav-item span {
    font-size: 14px;
    font-weight: 600;
    color: #2C3E50;
    text-align: center;
}

/* 主要内容区域 */
.content-grid {
    position: relative;
    z-index: 1;
}

/* 分类区域 */
.category-section {
    margin-bottom: 60px;
    background: rgba(255, 255, 255, 0.7);
    padding: 40px;
    border-radius: 20px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.08);
    border: 1px solid rgba(255, 255, 255, 0.3);
    backdrop-filter: blur(10px);
}

.category-title {
    display: flex;
    align-items: center;
    font-size: 36px;
    font-weight: 700;
    color: #2C3E50;
    margin-bottom: 30px;
    padding-bottom: 15px;
    border-bottom: 3px solid transparent;
    background: linear-gradient(90deg, #3498DB, #9B59B6, #E74C3C) bottom;
    background-size: 100% 3px;
    background-repeat: no-repeat;
}

.category-title i {
    font-size: 32px;
    margin-right: 15px;
    color: #3498DB;
    background: linear-gradient(45deg, #3498DB, #9B59B6);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.title-number {
    font-size: 48px;
    font-weight: 900;
    color: #BDC3C7;
    margin-right: 20px;
    font-family: 'Roboto', sans-serif;
}

/* 频道网格 */
.channels-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 20px;
    margin-top: 20px;
}

/* 频道卡片 */
.channel-card {
    background: rgba(255, 255, 255, 0.9);
    padding: 25px;
    border-radius: 15px;
    border: 2px solid transparent;
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
    box-shadow: 0 5px 15px rgba(0,0,0,0.08);
}

.channel-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, rgba(52, 152, 219, 0.05), rgba(155, 89, 182, 0.05));
    opacity: 0;
    transition: opacity 0.3s ease;
    pointer-events: none;
}

.channel-card:hover {
    transform: translateY(-5px);
    border-color: #3498DB;
    box-shadow: 0 15px 35px rgba(52, 152, 219, 0.2);
}

.channel-card:hover::before {
    opacity: 1;
}

.channel-card.featured {
    background: linear-gradient(135deg, rgba(231, 76, 60, 0.1), rgba(241, 196, 15, 0.1));
    border: 2px solid #E74C3C;
}

.channel-card.expert {
    background: linear-gradient(135deg, rgba(155, 89, 182, 0.1), rgba(52, 152, 219, 0.1));
    border: 2px solid #9B59B6;
}

.channel-name {
    font-size: 18px;
    font-weight: 700;
    color: #2C3E50;
    margin-bottom: 15px;
    line-height: 1.3;
    position: relative;
    z-index: 1;
}

.channel-link {
    display: inline-flex;
    align-items: center;
    color: #3498DB;
    text-decoration: none;
    font-size: 14px;
    font-weight: 500;
    transition: all 0.3s ease;
    position: relative;
    z-index: 1;
    font-family: 'Roboto', sans-serif;
}

.channel-link:hover {
    color: #2980B9;
    transform: translateX(5px);
}

.channel-link i {
    margin-right: 8px;
    font-size: 16px;
    transition: all 0.3s ease;
}

.channel-link:hover i {
    transform: scale(1.2);
}

.channel-description {
    font-size: 14px;
    color: #7F8C8D;
    margin-top: 10px;
    font-style: italic;
    position: relative;
    z-index: 1;
}

/* 响应式设计 */
@media (max-width: 1240px) {
    .container {
        width: 100%;
        max-width: 1200px;
        padding: 20px;
    }
    
    .main-title {
        font-size: 56px;
    }
    
    .category-nav {
        flex-wrap: wrap;
        gap: 10px;
    }
    
    .nav-item {
        flex: 1;
        min-width: 120px;
    }
}

@media (max-width: 768px) {
    .container {
        height: auto;
        min-height: 1800px;
    }
    
    .main-title {
        font-size: 42px;
    }
    
    .category-title {
        font-size: 28px;
    }
    
    .channels-grid {
        grid-template-columns: 1fr;
    }
    
    .category-nav {
        flex-direction: column;
    }
    
    .nav-item {
        flex-direction: row;
        justify-content: flex-start;
    }
    
    .nav-item i {
        margin-right: 10px;
        margin-bottom: 0;
    }
}

/* 动画效果 */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

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

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

/* 滚动条样式 */
::-webkit-scrollbar {
    width: 8px;
}

::-webkit-scrollbar-track {
    background: rgba(255, 255, 255, 0.1);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb {
    background: linear-gradient(45deg, #3498DB, #9B59B6);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: linear-gradient(45deg, #2980B9, #8E44AD);
}

/* 版权信息区域 */
.copyright-section {
    margin-top: 60px;
    padding: 30px 0;
    text-align: center;
    border-top: 2px solid rgba(52, 152, 219, 0.2);
    background: rgba(255, 255, 255, 0.3);
    border-radius: 15px;
    position: relative;
    z-index: 1;
}

.copyright-text {
    font-size: 14px;
    color: #7F8C8D;
    font-family: 'Roboto', sans-serif;
    font-weight: 400;
    letter-spacing: 0.5px;
    margin: 0;
    opacity: 0.8;
    transition: all 0.3s ease;
}

.copyright-section:hover .copyright-text {
    opacity: 1;
    color: #5D6D7E;
}

/* 回到顶部按钮样式 */
.back-to-top-btn {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    border: none;
    border-radius: 50%;
    background: linear-gradient(135deg, #3498DB, #9B59B6);
    color: white;
    font-size: 18px;
    cursor: pointer;
    box-shadow: 0 4px 15px rgba(52, 152, 219, 0.3);
    transition: all 0.3s ease;
    z-index: 1000;
    opacity: 0;
    visibility: hidden;
    transform: translateY(20px);
}

.back-to-top-btn.show {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.back-to-top-btn:hover {
    transform: translateY(-3px) scale(1.1);
    box-shadow: 0 8px 25px rgba(52, 152, 219, 0.4);
    background: linear-gradient(135deg, #2980B9, #8E44AD);
}

.back-to-top-btn:active {
    transform: translateY(-1px) scale(1.05);
    box-shadow: 0 4px 15px rgba(52, 152, 219, 0.3);
}

.back-to-top-btn i {
    transition: transform 0.3s ease;
}

.back-to-top-btn:hover i {
    transform: translateY(-2px);
}