:root {
  --font-body: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --spacing: 8px;
  --radius: 8px;
  --transition: 0.3s ease;
}

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

body {
  font-family: var(--font-body);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

body.ui-style-2 {
  background: #fff;
  color: #333;
}

body.ui-style-2 a {
  color: inherit;
  text-decoration: none;
}

body.ui-style-7 {
  background: #0f1419;
  color: #e8eaed;
}

body.ui-style-7 a {
  color: inherit;
  text-decoration: none;
}

body.ui-style-7 header {
  background: #1a1f29;
  border-bottom: 1px solid #2a3140;
}

body.ui-style-7 .site-logo {
  color: #00E5AA;
}

body.ui-style-7 .main-nav a {
  color: #b0b5bd;
}

body.ui-style-7 .main-nav a:hover,
body.ui-style-7 .main-nav a.active {
  color: #00E5AA;
}

body.ui-style-7 .hero-section {
  background: linear-gradient(135deg, #00E5AA 0%, #00B88A 100%);
  color: #0f1419;
}

body.ui-style-7 .section-title,
body.ui-style-7 .page-header h1,
body.ui-style-7 .detail-header h1 {
  color: #e8eaed;
}

body.ui-style-7 .page-header p {
  color: #b0b5bd;
}

body.ui-style-7 .video-card {
  background: #1a1f29;
}

body.ui-style-7 .video-title {
  color: #e8eaed;
}

body.ui-style-7 .video-meta {
  color: #6b737f;
}

body.ui-style-7 .video-one-line {
  color: #b0b5bd;
}

body.ui-style-7 .info-block {
  background: #1a1f29;
  border: 1px solid #2a3140;
}

body.ui-style-7 .info-block h2,
body.ui-style-7 .content-module h2 {
  color: #e8eaed;
}

body.ui-style-7 .info-label {
  color: #6b737f;
}

body.ui-style-7 .info-value {
  color: #e8eaed;
}

body.ui-style-7 .content-module p,
body.ui-style-7 .content-module li {
  color: #b0b5bd;
}

body.ui-style-7 .site-intro {
  background: #1a1f29;
  color: #b0b5bd;
  border: 1px solid #2a3140;
}

body.ui-style-7 .filter-bar {
  background: #1a1f29;
  border: 1px solid #2a3140;
}

body.ui-style-7 .filter-bar span {
  color: #b0b5bd;
}

body.ui-style-7 .top-item {
  background: #1a1f29;
}

body.ui-style-7 .top-info h3 {
  color: #e8eaed;
}

body.ui-style-7 .group h3 {
  color: #e8eaed;
  border-bottom-color: #00E5AA;
}

body.ui-style-7 .video-card--related {
  background: #1a1f29;
}

body.ui-style-7 .player-play-btn {
  background: rgba(0, 229, 170, 0.95);
}

body.ui-style-7 .player-play-btn:hover {
  background: #00E5AA;
}

body.ui-style-7 .back-to-top {
  background: #00E5AA;
  color: #0f1419;
}

header {
  background: #fff;
  border-bottom: 1px solid #e5e5e5;
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: 0 2px 8px rgba(0,0,0,0.05);
}

.header-inner {
  max-width: 1280px;
  margin: 0 auto;
  padding: calc(var(--spacing) * 2) calc(var(--spacing) * 3);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.site-logo {
  font-size: 24px;
  font-weight: 700;
  color: #ff6b35;
  flex-shrink: 0;
}

.main-nav {
  display: flex;
  gap: calc(var(--spacing) * 4);
  align-items: center;
}

.main-nav a {
  font-size: 15px;
  color: #666;
  transition: color var(--transition);
  white-space: nowrap;
}

.main-nav a:hover,
.main-nav a.active {
  color: #ff6b35;
}

main {
  max-width: 1280px;
  margin: 0 auto;
  padding: calc(var(--spacing) * 4) calc(var(--spacing) * 3);
}

.hero-section {
  background: linear-gradient(135deg, #ff6b35 0%, #ff8c61 100%);
  color: #fff;
  padding: calc(var(--spacing) * 8) calc(var(--spacing) * 4);
  border-radius: calc(var(--radius) * 2);
  margin-bottom: calc(var(--spacing) * 6);
  text-align: center;
}

.hero-section h1 {
  font-size: 42px;
  font-weight: 700;
  margin-bottom: calc(var(--spacing) * 3);
  line-height: 1.2;
}

.hero-section p {
  font-size: 18px;
  opacity: 0.95;
  max-width: 800px;
  margin: 0 auto;
}

.section-title {
  font-size: 28px;
  font-weight: 700;
  margin-bottom: calc(var(--spacing) * 4);
  color: #222;
}

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

.page-header h1 {
  font-size: 36px;
  font-weight: 700;
  margin-bottom: calc(var(--spacing) * 2);
  color: #222;
}

.page-header p {
  font-size: 16px;
  color: #666;
  line-height: 1.6;
}

.filter-bar {
  background: #f8f9fa;
  padding: calc(var(--spacing) * 2) calc(var(--spacing) * 3);
  border-radius: var(--radius);
  margin-bottom: calc(var(--spacing) * 4);
  display: flex;
  gap: calc(var(--spacing) * 2);
  flex-wrap: wrap;
}

.filter-bar span {
  color: #666;
  font-size: 14px;
}

.video-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: calc(var(--spacing) * 4);
  margin-bottom: calc(var(--spacing) * 6);
}

.video-card {
  background: #fff;
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: 0 2px 8px rgba(0,0,0,0.08);
  transition: transform var(--transition), box-shadow var(--transition);
}

.video-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 8px 16px rgba(0,0,0,0.12);
}

.video-card__link {
  display: block;
}

.video-cover {
  position: relative;
  width: 100%;
  padding-top: 140%;
  background: #f0f0f0;
  overflow: hidden;
}

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

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

.video-title {
  font-size: 16px;
  font-weight: 600;
  margin-bottom: calc(var(--spacing));
  color: #222;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.video-meta {
  font-size: 13px;
  color: #999;
  margin-bottom: calc(var(--spacing));
}

.video-one-line {
  font-size: 14px;
  color: #666;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.video-player-section {
  margin-bottom: calc(var(--spacing) * 6);
}

.video-player {
  background: #000;
  border-radius: calc(var(--radius) * 2);
  overflow: hidden;
  box-shadow: 0 4px 16px rgba(0,0,0,0.2);
}

.video-player-inner {
  position: relative;
  width: 100%;
  padding-top: 56.25%;
  background: linear-gradient(135deg, #1a1a1a 0%, #2d2d2d 100%);
}

.player-play-btn {
  position: absolute;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
  width: 80px;
  height: 80px;
  background: rgba(255, 107, 53, 0.95);
  border: none;
  border-radius: 50%;
  cursor: pointer;
  transition: all var(--transition);
  display: flex;
  align-items: center;
  justify-content: center;
}

.player-play-btn:hover {
  background: #ff6b35;
  transform: translate(-50%, -50%) scale(1.1);
}

.player-play-icon {
  font-size: 32px;
  color: #fff;
  margin-left: 4px;
}

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

.detail-header h1 {
  font-size: 36px;
  font-weight: 700;
  margin-bottom: calc(var(--spacing) * 3);
  color: #222;
  line-height: 1.3;
}

.info-block {
  background: #f8f9fa;
  padding: calc(var(--spacing) * 3);
  border-radius: var(--radius);
  margin-bottom: calc(var(--spacing) * 4);
}

.info-block h2 {
  font-size: 20px;
  font-weight: 600;
  margin-bottom: calc(var(--spacing) * 2);
  color: #222;
}

.info-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: calc(var(--spacing) * 2);
}

.info-item {
  display: flex;
  gap: calc(var(--spacing));
}

.info-label {
  font-weight: 600;
  color: #666;
  flex-shrink: 0;
}

.info-value {
  color: #333;
}

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

.content-module h2 {
  font-size: 24px;
  font-weight: 600;
  margin-bottom: calc(var(--spacing) * 3);
  color: #222;
}

.content-module p,
.content-module ul {
  font-size: 15px;
  line-height: 1.8;
  color: #444;
}

.content-module ul {
  list-style: none;
  padding-left: calc(var(--spacing) * 2);
}

.content-module li {
  margin-bottom: var(--spacing);
}

.content-module li::before {
  content: "•";
  color: #ff6b35;
  font-weight: bold;
  display: inline-block;
  width: 1em;
  margin-left: -1em;
}

.related-section {
  margin-top: calc(var(--spacing) * 8);
  padding-top: calc(var(--spacing) * 6);
  border-top: 2px solid #e5e5e5;
}

.related-section h2 {
  font-size: 28px;
  font-weight: 700;
  margin-bottom: calc(var(--spacing) * 4);
  color: #222;
}

.video-card--related {
  background: #f8f9fa;
}

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

.top-list__items {
  display: flex;
  flex-direction: column;
  gap: calc(var(--spacing) * 2);
}

.top-item {
  background: #fff;
  border-radius: var(--radius);
  padding: calc(var(--spacing) * 2);
  box-shadow: 0 2px 8px rgba(0,0,0,0.08);
  display: flex;
  gap: calc(var(--spacing) * 2);
  transition: transform var(--transition);
  align-items: center;
}

.top-item:hover {
  transform: translateX(4px);
}

.top-rank {
  flex-shrink: 0;
  width: 40px;
  height: 40px;
  background: linear-gradient(135deg, #ff6b35 0%, #ff8c61 100%);
  color: #fff;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 18px;
}

.top-rank.gold {
  background: linear-gradient(135deg, #ffd700 0%, #ffed4e 100%);
  color: #333;
}

.top-rank.silver {
  background: linear-gradient(135deg, #c0c0c0 0%, #e0e0e0 100%);
  color: #333;
}

.top-rank.bronze {
  background: linear-gradient(135deg, #cd7f32 0%, #e9a758 100%);
  color: #fff;
}

.top-cover {
  flex-shrink: 0;
  width: 80px;
  height: 112px;
  border-radius: calc(var(--radius) / 2);
  overflow: hidden;
  background: #f0f0f0;
}

.top-cover img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.top-info {
  flex: 1;
  min-width: 0;
}

.top-info h3 {
  font-size: 16px;
  font-weight: 600;
  margin-bottom: calc(var(--spacing) / 2);
  color: #222;
}

.top-info .video-meta {
  margin-bottom: calc(var(--spacing) / 2);
}

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

.group h3 {
  font-size: 22px;
  font-weight: 600;
  margin-bottom: calc(var(--spacing) * 3);
  color: #222;
  padding-bottom: calc(var(--spacing));
  border-bottom: 2px solid #ff6b35;
}

.group__grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: calc(var(--spacing) * 3);
}

.site-intro {
  background: #f8f9fa;
  padding: calc(var(--spacing) * 4);
  border-radius: var(--radius);
  margin-bottom: calc(var(--spacing) * 6);
  line-height: 1.8;
  color: #555;
}

footer {
  background: #2d2d2d;
  color: #999;
  padding: calc(var(--spacing) * 4) calc(var(--spacing) * 3);
  margin-top: calc(var(--spacing) * 8);
  text-align: center;
  font-size: 14px;
}

.back-to-top {
  position: fixed;
  right: calc(var(--spacing) * 3);
  bottom: calc(var(--spacing) * 3);
  width: 48px;
  height: 48px;
  background: #ff6b35;
  color: #fff;
  border: none;
  border-radius: 50%;
  cursor: pointer;
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--transition), transform var(--transition);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 20px;
  box-shadow: 0 4px 12px rgba(0,0,0,0.2);
}

.back-to-top.visible {
  opacity: 1;
  pointer-events: auto;
}

.back-to-top:hover {
  transform: translateY(-4px);
}

@media (max-width: 768px) {
  .header-inner {
    padding: calc(var(--spacing) * 1.5);
  }

  .site-logo {
    font-size: 20px;
  }

  .main-nav {
    gap: calc(var(--spacing) * 2);
    font-size: 13px;
  }

  .main-nav a {
    font-size: 13px;
  }

  main {
    padding: calc(var(--spacing) * 2) calc(var(--spacing) * 2);
  }

  .hero-section {
    padding: calc(var(--spacing) * 4) calc(var(--spacing) * 2);
  }

  .hero-section h1 {
    font-size: 28px;
  }

  .hero-section p {
    font-size: 15px;
  }

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

  .page-header h1 {
    font-size: 26px;
  }

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

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

  .video-info {
    padding: calc(var(--spacing) * 1.5);
  }

  .video-title {
    font-size: 14px;
  }

  .detail-header h1 {
    font-size: 26px;
  }

  .content-module h2 {
    font-size: 20px;
  }

  .info-grid {
    grid-template-columns: 1fr;
  }

  .top-item {
    flex-wrap: wrap;
  }

  .top-cover {
    width: 60px;
    height: 84px;
  }

  .group__grid {
    grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
    gap: calc(var(--spacing) * 2);
  }
}