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

html {
  scroll-behavior: smooth;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Helvetica Neue', Arial, sans-serif;
  line-height: 1.6;
  color: #333;
  background: #f8f9fa;
}

.app {
  min-height: 100vh;
}

/* 头部导航栏 */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  box-shadow: 0 2px 15px rgba(0,0,0,0.1);
  z-index: 1000;
}

.header-content {
  max-width: 1400px;
  margin: 0 auto;
  padding: 0 20px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 70px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 24px;
  font-weight: bold;
  color: white;
  cursor: pointer;
}

.logo-icon {
  font-size: 32px;
}

.nav {
  display: flex;
  gap: 5px;
}

.nav a {
  display: flex;
  align-items: center;
  gap: 5px;
  padding: 10px 15px;
  color: rgba(255,255,255,0.9);
  text-decoration: none;
  border-radius: 8px;
  transition: all 0.3s ease;
  font-size: 14px;
}

.nav a:hover {
  background: rgba(255,255,255,0.15);
  color: white;
}

.nav a.active {
  background: rgba(255,255,255,0.25);
  color: white;
  font-weight: 600;
}

.nav-icon {
  font-size: 18px;
}

/* 首页横幅 */
.hero {
  margin-top: 70px;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
  padding: 80px 20px 60px;
  text-align: center;
}

.hero-content h1 {
  font-size: 48px;
  margin-bottom: 20px;
  font-weight: 700;
}

.hero-content p {
  font-size: 20px;
  margin-bottom: 40px;
  opacity: 0.95;
}

.hero-buttons {
  display: flex;
  gap: 20px;
  justify-content: center;
  margin-bottom: 60px;
}

.btn-primary, .btn-secondary {
  padding: 14px 32px;
  font-size: 16px;
  border: none;
  border-radius: 8px;
  cursor: pointer;
  font-weight: 600;
  transition: all 0.3s ease;
}

.btn-primary {
  background: white;
  color: #667eea;
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 5px 20px rgba(255,255,255,0.3);
}

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

.btn-secondary:hover {
  background: rgba(255,255,255,0.3);
  transform: translateY(-2px);
}

.hero-stats {
  display: flex;
  gap: 60px;
  justify-content: center;
}

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

.stat-number {
  font-size: 36px;
  font-weight: 700;
  margin-bottom: 8px;
}

.stat-label {
  font-size: 14px;
  opacity: 0.9;
}

/* 通用区块样式 */
.section {
  padding: 80px 20px;
}

.container {
  max-width: 1400px;
  margin: 0 auto;
}

.section-title {
  font-size: 36px;
  font-weight: 700;
  text-align: center;
  margin-bottom: 15px;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
}

.title-icon {
  font-size: 40px;
}

.section-subtitle {
  text-align: center;
  font-size: 18px;
  color: #666;
  margin-bottom: 50px;
}

/* 栏目分类 */
.categories-section {
  background: white;
}

.categories-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 25px;
}

.category-card {
  background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
  padding: 30px;
  border-radius: 15px;
  text-align: center;
  transition: all 0.3s ease;
  cursor: pointer;
}

.category-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 10px 30px rgba(0,0,0,0.15);
}

.category-icon {
  font-size: 60px;
  margin-bottom: 15px;
}

.category-card h3 {
  font-size: 22px;
  margin-bottom: 10px;
  color: #333;
}

.category-card p {
  color: #666;
  font-size: 14px;
  margin-bottom: 15px;
}

.category-stats {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  font-size: 13px;
  color: #888;
}

/* 热门排行榜 */
.ranking-section {
  background: #f8f9fa;
}

.ranking-grid {
  display: grid;
  gap: 20px;
}

.ranking-card {
  background: white;
  padding: 25px;
  border-radius: 15px;
  display: flex;
  gap: 20px;
  align-items: center;
  transition: all 0.3s ease;
  box-shadow: 0 2px 10px rgba(0,0,0,0.05);
}

.ranking-card:hover {
  transform: translateX(5px);
  box-shadow: 0 5px 20px rgba(0,0,0,0.1);
}

.ranking-badge {
  font-size: 32px;
  font-weight: 700;
  color: #ccc;
  min-width: 50px;
  text-align: center;
}

.ranking-card.top1 .ranking-badge {
  color: #FFD700;
}

.ranking-card.top2 .ranking-badge {
  color: #C0C0C0;
}

.ranking-card.top3 .ranking-badge {
  color: #CD7F32;
}

.ranking-thumbnail {
  width: 120px;
  height: 90px;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 50px;
  flex-shrink: 0;
}

.ranking-info {
  flex: 1;
}

.ranking-info h3 {
  font-size: 20px;
  margin-bottom: 10px;
  color: #333;
}

.ranking-meta {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 14px;
  color: #888;
  margin-bottom: 8px;
}

.ranking-desc {
  color: #666;
  font-size: 14px;
  line-height: 1.6;
}

/* 最新视频 */
.latest-section {
  background: white;
}

.video-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 25px;
}

.video-card {
  background: #f8f9fa;
  border-radius: 15px;
  overflow: hidden;
  transition: all 0.3s ease;
  cursor: pointer;
}

.video-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 10px 30px rgba(0,0,0,0.15);
}

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

.video-thumbnail-icon {
  font-size: 80px;
}

.video-duration {
  position: absolute;
  bottom: 10px;
  right: 10px;
  background: rgba(0,0,0,0.7);
  color: white;
  padding: 4px 8px;
  border-radius: 4px;
  font-size: 12px;
  font-weight: 600;
}

.video-info {
  padding: 20px;
}

.video-info h3 {
  font-size: 16px;
  margin-bottom: 10px;
  color: #333;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.video-meta {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  color: #888;
  margin-bottom: 5px;
}

.video-category {
  color: #667eea;
  font-weight: 600;
}

.video-time {
  font-size: 12px;
  color: #999;
}

/* 推荐内容 */
.recommended-section {
  background: #f8f9fa;
}

.recommended-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
  gap: 25px;
}

.recommended-card {
  background: white;
  padding: 30px;
  border-radius: 15px;
  transition: all 0.3s ease;
  position: relative;
  box-shadow: 0 2px 10px rgba(0,0,0,0.05);
}

.recommended-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 10px 30px rgba(0,0,0,0.15);
}

.recommended-card.featured {
  grid-column: span 2;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
}

.recommended-badge {
  position: absolute;
  top: 15px;
  right: 15px;
  background: rgba(255,255,255,0.9);
  color: #667eea;
  padding: 5px 12px;
  border-radius: 20px;
  font-size: 12px;
  font-weight: 600;
}

.recommended-icon {
  font-size: 50px;
  margin-bottom: 15px;
}

.recommended-card h3 {
  font-size: 22px;
  margin-bottom: 15px;
  font-weight: 600;
}

.recommended-card p {
  font-size: 15px;
  line-height: 1.8;
  margin-bottom: 20px;
  opacity: 0.9;
}

.recommended-card:not(.featured) p {
  color: #666;
}

.recommended-stats {
  display: flex;
  gap: 15px;
  font-size: 14px;
  font-weight: 500;
}

/* 社区讨论 */
.community-section {
  background: white;
}

.community-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(400px, 1fr));
  gap: 25px;
}

.discussion-card {
  background: #f8f9fa;
  padding: 25px;
  border-radius: 15px;
  transition: all 0.3s ease;
  cursor: pointer;
  border-left: 4px solid transparent;
}

.discussion-card:hover {
  transform: translateY(-3px);
  box-shadow: 0 8px 25px rgba(0,0,0,0.1);
  border-left-color: #667eea;
}

.discussion-card.hot {
  background: linear-gradient(135deg, #fff5f5 0%, #ffe6e6 100%);
  border-left-color: #ff4444;
}

.discussion-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 15px;
}

.discussion-user {
  display: flex;
  gap: 12px;
  align-items: center;
}

.user-avatar {
  width: 45px;
  height: 45px;
  border-radius: 50%;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 24px;
}

.user-name {
  font-weight: 600;
  color: #333;
  font-size: 14px;
}

.discussion-time {
  font-size: 12px;
  color: #888;
}

.discussion-tag {
  padding: 5px 12px;
  border-radius: 20px;
  font-size: 12px;
  font-weight: 600;
  background: #e3f2fd;
  color: #1976d2;
}

.discussion-tag.hot-tag {
  background: #ffebee;
  color: #c62828;
}

.discussion-card h3 {
  font-size: 18px;
  margin-bottom: 12px;
  color: #333;
  line-height: 1.4;
}

.discussion-card p {
  color: #666;
  font-size: 14px;
  line-height: 1.7;
  margin-bottom: 15px;
}

.discussion-stats {
  display: flex;
  gap: 15px;
  font-size: 13px;
  color: #888;
}

/* 关于我们 */
.about-section {
  background: #f8f9fa;
}

.about-content {
  display: grid;
  gap: 50px;
}

.about-intro {
  background: white;
  padding: 40px;
  border-radius: 15px;
  box-shadow: 0 2px 10px rgba(0,0,0,0.05);
}

.about-intro h3 {
  font-size: 28px;
  margin-bottom: 20px;
  color: #333;
}

.about-intro p {
  font-size: 16px;
  line-height: 1.8;
  color: #666;
  margin-bottom: 15px;
}

.about-features {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: 25px;
}

.feature-item {
  background: white;
  padding: 30px;
  border-radius: 15px;
  text-align: center;
  box-shadow: 0 2px 10px rgba(0,0,0,0.05);
  transition: all 0.3s ease;
}

.feature-item:hover {
  transform: translateY(-5px);
  box-shadow: 0 10px 30px rgba(0,0,0,0.1);
}

.feature-icon {
  font-size: 50px;
  margin-bottom: 15px;
}

.feature-item h4 {
  font-size: 20px;
  margin-bottom: 10px;
  color: #333;
}

.feature-item p {
  color: #666;
  font-size: 14px;
  line-height: 1.6;
}

.about-contact {
  background: white;
  padding: 40px;
  border-radius: 15px;
  box-shadow: 0 2px 10px rgba(0,0,0,0.05);
}

.about-contact h3 {
  font-size: 28px;
  margin-bottom: 25px;
  color: #333;
}

.contact-info {
  display: grid;
  gap: 20px;
}

.contact-item {
  display: flex;
  align-items: center;
  gap: 15px;
  font-size: 16px;
  color: #666;
}

.contact-icon {
  font-size: 24px;
}

/* 底部导航栏 */
.footer {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
  padding: 40px 20px 30px;
}

.footer-nav {
  display: flex;
  justify-content: center;
  gap: 40px;
  margin-bottom: 40px;
}

.footer-nav a {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  color: white;
  text-decoration: none;
  transition: all 0.3s ease;
  opacity: 0.9;
}

.footer-nav a:hover {
  opacity: 1;
  transform: translateY(-3px);
}

.footer-icon {
  font-size: 28px;
}

.footer-info {
  text-align: center;
  border-top: 1px solid rgba(255,255,255,0.2);
  padding-top: 30px;
}

.footer-info p {
  margin-bottom: 15px;
  opacity: 0.9;
}

.footer-links {
  display: flex;
  justify-content: center;
  gap: 15px;
  margin-bottom: 15px;
  flex-wrap: wrap;
}

.footer-links a {
  color: white;
  text-decoration: none;
  opacity: 0.9;
  transition: opacity 0.3s ease;
}

.footer-links a:hover {
  opacity: 1;
  text-decoration: underline;
}

.footer-desc {
  font-size: 14px;
  opacity: 0.8;
}

/* 响应式设计 */
@media (max-width: 1200px) {
  .recommended-card.featured {
    grid-column: span 1;
  }
}

@media (max-width: 768px) {
  .header-content {
    flex-direction: column;
    height: auto;
    padding: 15px 20px;
  }

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

  .nav a {
    padding: 8px 12px;
    font-size: 12px;
  }

  .hero {
    padding: 60px 20px 40px;
  }

  .hero-content h1 {
    font-size: 32px;
  }

  .hero-content p {
    font-size: 16px;
  }

  .hero-buttons {
    flex-direction: column;
    align-items: center;
  }

  .hero-stats {
    flex-direction: column;
    gap: 30px;
  }

  .section {
    padding: 50px 20px;
  }

  .section-title {
    font-size: 28px;
  }

  .categories-grid,
  .video-grid,
  .recommended-grid,
  .community-grid {
    grid-template-columns: 1fr;
  }

  .ranking-card {
    flex-direction: column;
    text-align: center;
  }

  .footer-nav {
    gap: 20px;
  }
}

/* 平滑滚动动画 */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

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