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

:root {
  --spacing: 8px;
  --primary: #00C75A;
  --text: #333;
  --bg: #fff;
  --gray: #f5f5f5;
  --border: #e0e0e0;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  line-height: 1.6;
  color: var(--text);
  background: var(--bg);
}

.ui-style-7 {
  --primary: #00A1D6;
  --secondary: #FB7299;
}

a {
  text-decoration: none;
  color: inherit;
}

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

.container {
  max-width: 1400px;
  margin: 0 auto;
  padding: 0 calc(var(--spacing) * 2);
}

header {
  background: var(--bg);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: 0 2px 8px rgba(0,0,0,0.05);
}

.main-nav {
  display: flex;
  align-items: center;
  gap: calc(var(--spacing) * 3);
  padding: calc(var(--spacing) * 2);
  max-width: 1400px;
  margin: 0 auto;
}

.main-nav .logo {
  font-size: 24px;
  font-weight: 700;
  color: var(--primary);
  white-space: nowrap;
}

.nav-links {
  display: flex;
  gap: calc(var(--spacing) * 3);
  flex-wrap: nowrap;
  overflow-x: auto;
  scrollbar-width: none;
}

.nav-links::-webkit-scrollbar {
  display: none;
}

.nav-links a {
  white-space: nowrap;
  padding: calc(var(--spacing)) calc(var(--spacing) * 2);
  border-radius: calc(var(--spacing) * 2);
  transition: all 0.3s ease;
  font-weight: 500;
}

.nav-links a:hover,
.nav-links a.active {
  background: var(--primary);
  color: white;
}

.hero-section {
  background: linear-gradient(135deg, var(--primary) 0%, #0088cc 100%);
  color: white;
  padding: calc(var(--spacing) * 8) calc(var(--spacing) * 2);
  text-align: center;
}

.hero-title {
  font-size: 32px;
  margin-bottom: calc(var(--spacing) * 3);
  font-weight: 700;
}

.hero-desc {
  font-size: 18px;
  max-width: 800px;
  margin: 0 auto;
  line-height: 1.8;
  opacity: 0.95;
}

.intro-section {
  padding: calc(var(--spacing) * 6) 0;
  background: var(--gray);
}

.intro-section p {
  max-width: 1000px;
  margin: 0 auto;
  line-height: 2;
  font-size: 16px;
  text-align: justify;
}

.content-section {
  padding: calc(var(--spacing) * 6) 0;
}

.section-title {
  font-size: 28px;
  margin-bottom: calc(var(--spacing) * 4);
  font-weight: 700;
  position: relative;
  padding-left: calc(var(--spacing) * 2);
}

.section-title::before {
  content: '';
  position: absolute;
  left: 0;
  top: 50%;
  transform: translateY(-50%);
  width: 4px;
  height: 28px;
  background: var(--primary);
  border-radius: 2px;
}

.video-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: calc(var(--spacing) * 3);
}

.video-card {
  background: white;
  border-radius: calc(var(--spacing) * 2);
  overflow: hidden;
  transition: all 0.3s ease;
  box-shadow: 0 2px 8px rgba(0,0,0,0.08);
}

.video-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 8px 24px rgba(0,0,0,0.15);
}

.video-card__link {
  display: block;
}

.video-cover {
  position: relative;
  padding-top: 140%;
  overflow: hidden;
  background: var(--gray);
}

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

.play-overlay {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 60px;
  height: 60px;
  background: rgba(0,0,0,0.6);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-size: 24px;
  opacity: 0;
  transition: opacity 0.3s ease;
}

.video-card:hover .play-overlay {
  opacity: 1;
}

.video-info {
  padding: calc(var(--spacing) * 2);
}

.video-title {
  font-size: 18px;
  font-weight: 600;
  margin-bottom: calc(var(--spacing));
  overflow: hidden;
  text-overflow: ellipsis;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  line-height: 1.4;
}

.video-one-line {
  font-size: 14px;
  color: #666;
  margin-bottom: calc(var(--spacing));
  overflow: hidden;
  text-overflow: ellipsis;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
}

.video-meta {
  display: flex;
  gap: calc(var(--spacing));
  flex-wrap: wrap;
  font-size: 13px;
  color: #999;
}

.video-meta span {
  padding: calc(var(--spacing) / 2) calc(var(--spacing));
  background: var(--gray);
  border-radius: calc(var(--spacing));
}

.list-main {
  min-height: 80vh;
  padding: calc(var(--spacing) * 4) 0;
}

.page-header {
  margin-bottom: calc(var(--spacing) * 5);
  text-align: center;
}

.page-header h1 {
  font-size: 36px;
  margin-bottom: calc(var(--spacing) * 2);
  font-weight: 700;
}

.page-desc {
  font-size: 16px;
  color: #666;
  max-width: 800px;
  margin: 0 auto;
  line-height: 1.8;
}

.top-list__items {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: calc(var(--spacing) * 3);
}

.top-list__item {
  background: white;
  border-radius: calc(var(--spacing) * 2);
  padding: calc(var(--spacing) * 2);
  display: flex;
  gap: calc(var(--spacing) * 2);
  align-items: center;
  box-shadow: 0 2px 8px rgba(0,0,0,0.08);
  transition: all 0.3s ease;
}

.top-list__item:hover {
  box-shadow: 0 4px 16px rgba(0,0,0,0.15);
}

.rank-badge {
  font-size: 32px;
  font-weight: 700;
  color: var(--primary);
  min-width: 60px;
  text-align: center;
}

.top-list__item .video-cover {
  width: 120px;
  padding-top: 168px;
  flex-shrink: 0;
  border-radius: calc(var(--spacing));
}

.top-list__item .video-info {
  flex: 1;
  padding: 0;
}

.layout__with-sidebar {
  display: grid;
  grid-template-columns: 260px 1fr;
  gap: calc(var(--spacing) * 4);
}

.layout__side--filters {
  background: white;
  padding: calc(var(--spacing) * 3);
  border-radius: calc(var(--spacing) * 2);
  height: fit-content;
  position: sticky;
  top: calc(var(--spacing) * 10);
}

.layout__side--filters h3 {
  margin-bottom: calc(var(--spacing) * 2);
}

.group {
  margin-bottom: calc(var(--spacing) * 6);
}

.group__title {
  font-size: 24px;
  margin-bottom: calc(var(--spacing) * 3);
  font-weight: 700;
  color: var(--primary);
}

.group__grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: calc(var(--spacing) * 3);
}

.video-player-section {
  background: #000;
  padding: calc(var(--spacing) * 4) 0;
}

.video-player {
  max-width: 1200px;
  margin: 0 auto;
}

.video-player-inner {
  position: relative;
  width: 100%;
  padding-top: 56.25%;
  background: #000;
  border-radius: calc(var(--spacing) * 2);
  overflow: hidden;
}

.player-play-btn {
  position: absolute;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
  width: 80px;
  height: 80px;
  background: rgba(255,255,255,0.9);
  border: none;
  border-radius: 50%;
  cursor: pointer;
  transition: all 0.3s ease;
  display: flex;
  align-items: center;
  justify-content: center;
}

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

.player-play-icon {
  font-size: 36px;
  color: var(--primary);
  margin-left: 4px;
}

.detail-content {
  max-width: 900px;
  margin: 0 auto;
  padding: calc(var(--spacing) * 4) calc(var(--spacing) * 2);
}

.detail-content h1 {
  font-size: 36px;
  margin-bottom: calc(var(--spacing) * 4);
  font-weight: 700;
}

.detail-module {
  margin-bottom: calc(var(--spacing) * 5);
}

.detail-module h2 {
  font-size: 24px;
  margin-bottom: calc(var(--spacing) * 2);
  font-weight: 700;
  color: var(--primary);
}

.detail-module p {
  line-height: 2;
  font-size: 16px;
  text-align: justify;
}

.basic-info {
  background: var(--gray);
  padding: calc(var(--spacing) * 3);
  border-radius: calc(var(--spacing) * 2);
  margin-bottom: calc(var(--spacing) * 5);
}

.info-list {
  display: grid;
  grid-template-columns: 80px 1fr;
  gap: calc(var(--spacing) * 2);
  margin-top: calc(var(--spacing) * 2);
}

.info-list dt {
  font-weight: 600;
  color: #666;
}

.info-list dd {
  color: #333;
}

.tag-list {
  display: flex;
  flex-wrap: wrap;
  gap: calc(var(--spacing));
}

.tag {
  padding: calc(var(--spacing)) calc(var(--spacing) * 2);
  background: var(--primary);
  color: white;
  border-radius: calc(var(--spacing) * 2);
  font-size: 14px;
}

.related-section {
  margin-top: calc(var(--spacing) * 8);
  padding-top: calc(var(--spacing) * 4);
  border-top: 2px solid var(--border);
}

.related-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: calc(var(--spacing) * 3);
  margin-top: calc(var(--spacing) * 3);
}

.video-card--related {
  box-shadow: 0 2px 8px rgba(0,0,0,0.08);
}

footer {
  background: var(--gray);
  padding: calc(var(--spacing) * 4) 0;
  text-align: center;
  margin-top: calc(var(--spacing) * 8);
  color: #666;
  font-size: 14px;
}

.back-to-top {
  position: fixed;
  bottom: calc(var(--spacing) * 4);
  right: calc(var(--spacing) * 4);
  width: 48px;
  height: 48px;
  background: var(--primary);
  color: white;
  border: none;
  border-radius: 50%;
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transition: all 0.3s ease;
  font-size: 20px;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 4px 12px rgba(0,0,0,0.15);
}

.back-to-top.visible {
  opacity: 1;
  visibility: visible;
}

@media (max-width: 768px) {
  .main-nav {
    flex-direction: column;
    gap: calc(var(--spacing) * 2);
    align-items: stretch;
  }

  .nav-links {
    justify-content: flex-start;
    gap: calc(var(--spacing) * 2);
    padding-bottom: calc(var(--spacing));
  }

  .nav-links a {
    padding: calc(var(--spacing)) calc(var(--spacing) * 1.5);
    font-size: 14px;
  }

  .hero-title {
    font-size: 24px;
  }

  .hero-desc {
    font-size: 16px;
  }

  .video-grid {
    grid-template-columns: repeat(auto-fill, minmax(160px, 1fr));
    gap: calc(var(--spacing) * 2);
  }

  .video-cover {
    padding-top: 140%;
  }

  .video-title {
    font-size: 15px;
  }

  .layout__with-sidebar {
    grid-template-columns: 1fr;
  }

  .layout__side--filters {
    position: static;
  }

  .top-list__item {
    flex-direction: column;
    align-items: flex-start;
  }

  .top-list__item .video-cover {
    width: 100%;
    max-width: 200px;
  }

  .detail-content h1 {
    font-size: 28px;
  }

  .related-grid {
    grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
  }
}