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

:root {
  --primary-color: #2563eb;
  --secondary-color: #64748b;
  --text-color: #1e293b;
  --bg-color: #ffffff;
  --card-bg: #f8fafc;
  --border-color: #e2e8f0;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans", sans-serif;
  line-height: 1.6;
  color: var(--text-color);
  background: var(--bg-color);
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

.site-header {
  background: #fff;
  border-bottom: 1px solid var(--border-color);
  position: sticky;
  top: 0;
  z-index: 1000;
}

.header-content {
  max-width: 1200px;
  margin: 0 auto;
  padding: 16px 20px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.site-logo a {
  font-size: 24px;
  font-weight: bold;
  color: var(--primary-color);
  text-decoration: none;
}

.site-nav {
  display: flex;
  gap: 24px;
  white-space: nowrap;
  overflow: hidden;
}

.site-nav a {
  color: var(--text-color);
  text-decoration: none;
  transition: color 0.3s;
}

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

.main-content {
  min-height: 70vh;
  padding: 40px 0;
}

.hero-section {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
  padding: 60px 20px;
  text-align: center;
  margin-bottom: 40px;
}

.hero-title {
  font-size: 28px;
  line-height: 1.4;
  margin-bottom: 16px;
}

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

.intro-section {
  margin-bottom: 40px;
}

.site-intro {
  line-height: 1.8;
  color: var(--secondary-color);
  text-align: center;
  max-width: 900px;
  margin: 0 auto;
}

.video-module {
  margin-bottom: 50px;
}

.module-title {
  font-size: 24px;
  margin-bottom: 24px;
  padding-bottom: 12px;
  border-bottom: 2px solid var(--primary-color);
}

.video-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 24px;
}

.video-card {
  background: var(--card-bg);
  border-radius: 8px;
  overflow: hidden;
  transition: transform 0.3s, box-shadow 0.3s;
}

.video-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 8px 16px rgba(0, 0, 0, 0.1);
}

.video-card__link {
  text-decoration: none;
  color: inherit;
  display: block;
}

.video-cover {
  position: relative;
  padding-top: 56.25%;
  background: #ddd;
  overflow: hidden;
}

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

.video-info {
  padding: 16px;
}

.video-title {
  font-size: 18px;
  margin-bottom: 8px;
  font-weight: 600;
}

.video-one-line {
  font-size: 14px;
  color: var(--secondary-color);
  margin-bottom: 12px;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.video-meta {
  display: flex;
  gap: 12px;
  font-size: 13px;
  color: var(--secondary-color);
}

.page-header {
  margin-bottom: 32px;
}

.page-header h1 {
  font-size: 32px;
  margin-bottom: 12px;
}

.page-desc {
  color: var(--secondary-color);
  font-size: 16px;
}

.page--with-sidebar {
  display: grid;
  grid-template-columns: 250px 1fr;
  gap: 32px;
}

.layout__side--filters {
  background: var(--card-bg);
  padding: 24px;
  border-radius: 8px;
  height: fit-content;
}

.top-list__items {
  list-style: none;
}

.top-item {
  display: flex;
  gap: 16px;
  align-items: center;
  padding: 20px;
  margin-bottom: 16px;
  background: var(--card-bg);
  border-radius: 8px;
  transition: box-shadow 0.3s;
}

.top-item:hover {
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
}

.top-rank {
  font-size: 32px;
  font-weight: bold;
  color: var(--primary-color);
  min-width: 50px;
  text-align: center;
}

.top-item__link {
  display: flex;
  gap: 16px;
  flex: 1;
  text-decoration: none;
  color: inherit;
}

.top-item .video-cover {
  width: 120px;
  height: 68px;
  padding-top: 0;
  flex-shrink: 0;
}

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

.group {
  margin-bottom: 48px;
}

.group__title {
  font-size: 24px;
  margin-bottom: 20px;
  color: var(--primary-color);
}

.video-player-section {
  margin-bottom: 40px;
}

.video-player {
  max-width: 1000px;
  margin: 0 auto;
}

.video-player-inner {
  position: relative;
  width: 100%;
  padding-top: 56.25%;
  background: #000;
  border-radius: 8px;
  overflow: hidden;
}

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

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

.player-play-icon {
  font-size: 32px;
  color: var(--primary-color);
}

.video-header {
  margin-bottom: 32px;
}

.video-header h1 {
  font-size: 36px;
}

.video-basic-info {
  background: var(--card-bg);
  padding: 24px;
  border-radius: 8px;
  margin-bottom: 32px;
}

.video-basic-info h2 {
  font-size: 20px;
  margin-bottom: 16px;
}

.info-list {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 12px 24px;
}

.info-list dt {
  font-weight: 600;
  color: var(--secondary-color);
}

.info-list dd {
  color: var(--text-color);
}

.detail-module {
  margin-bottom: 32px;
  padding: 24px;
  background: var(--card-bg);
  border-radius: 8px;
}

.detail-module h2 {
  font-size: 22px;
  margin-bottom: 16px;
  color: var(--primary-color);
}

.module-content p {
  line-height: 1.8;
  margin-bottom: 12px;
}

.tag-cloud {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.tag {
  padding: 6px 16px;
  background: white;
  border: 1px solid var(--border-color);
  border-radius: 20px;
  font-size: 14px;
  color: var(--text-color);
}

.site-footer {
  background: #1e293b;
  color: white;
  padding: 32px 0;
  margin-top: 60px;
  text-align: center;
}

.back-to-top {
  position: fixed;
  bottom: 40px;
  right: 40px;
  width: 50px;
  height: 50px;
  background: var(--primary-color);
  color: white;
  border: none;
  border-radius: 50%;
  cursor: pointer;
  display: none;
  align-items: center;
  justify-content: center;
  font-size: 20px;
  transition: background 0.3s;
}

.back-to-top.visible {
  display: flex;
}

.back-to-top:hover {
  background: #1d4ed8;
}

.ui-style-2 {
  --primary-color: #f97316;
  --bg-color: #fffbeb;
}

.ui-style-2 .hero-section {
  background: linear-gradient(135deg, #fb923c 0%, #f97316 100%);
}

@media (max-width: 768px) {
  .header-content {
    flex-direction: column;
    gap: 12px;
  }

  .site-nav {
    gap: 16px;
    font-size: 14px;
  }

  .hero-title {
    font-size: 22px;
  }

  .hero-desc {
    font-size: 14px;
  }

  .video-grid {
    grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
    gap: 16px;
  }

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

  .top-item {
    flex-direction: column;
  }

  .top-item .video-cover {
    width: 100%;
    height: auto;
    padding-top: 56.25%;
  }

  .video-cover {
    padding-top: 56.25%;
  }
}