* {
  box-sizing: border-box;
}

body {
  margin: 0;
  padding: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans", sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol";
  background: #f8f9fa;
  color: #2c3e50;
  line-height: 1.7;
  font-size: 16px;
}

header {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  box-shadow: 0 2px 10px rgba(0,0,0,0.1);
  position: sticky;
  top: 0;
  z-index: 1000;
}

.logo {
  text-align: center;
  font-size: 24px;
  font-weight: 700;
  color: white;
  padding: 20px 0 10px;
  letter-spacing: 2px;
}

nav ul {
  display: flex;
  flex-wrap: nowrap;
  justify-content: space-between;
  align-items: center;
  list-style: none;
  margin: 0;
  padding: 0;
  background: rgba(0,0,0,0.1);
}

nav ul li {
  flex: 1 1 0;
  min-width: 0;
  text-align: center;
  border-right: 1px solid rgba(255,255,255,0.1);
}

nav ul li:last-child {
  border-right: none;
}

nav ul li a {
  display: block;
  color: white;
  text-decoration: none;
  padding: 15px 10px;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  font-weight: 500;
  transition: all 0.3s ease;
}

nav ul li a:hover {
  background: rgba(255,255,255,0.2);
  transform: translateY(-2px);
}

main {
  max-width: 1200px;
  margin: 0 auto;
  padding: 30px 20px;
  min-height: calc(100vh - 200px);
}

.hero {
  text-align: center;
  padding: 40px 20px;
  background: white;
  border-radius: 12px;
  box-shadow: 0 4px 20px rgba(0,0,0,0.08);
  margin-bottom: 40px;
}

.hero h1 {
  font-size: 32px;
  color: #667eea;
  margin: 0 0 20px;
  font-weight: 700;
  line-height: 1.3;
}

.hero .intro {
  font-size: 16px;
  color: #666;
  max-width: 900px;
  margin: 0 auto;
  line-height: 1.8;
}

section {
  margin-bottom: 50px;
}

section h2 {
  font-size: 26px;
  color: #2c3e50;
  margin: 0 0 25px;
  padding-bottom: 12px;
  border-bottom: 3px solid #667eea;
  font-weight: 700;
}

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

.video-card {
  background: white;
  padding: 25px;
  border-radius: 10px;
  box-shadow: 0 2px 12px rgba(0,0,0,0.08);
  transition: all 0.3s ease;
  border: 1px solid #e8e8e8;
}

.video-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 8px 25px rgba(102, 126, 234, 0.15);
  border-color: #667eea;
}

.video-card h3 {
  margin: 0 0 12px;
  font-size: 18px;
  color: #2c3e50;
  font-weight: 600;
}

.video-card h3 a {
  color: #2c3e50;
  text-decoration: none;
  transition: color 0.3s;
}

.video-card h3 a:hover {
  color: #667eea;
}

.video-card .rank {
  display: inline-block;
  background: linear-gradient(135deg, #667eea, #764ba2);
  color: white;
  padding: 2px 8px;
  border-radius: 4px;
  font-size: 14px;
  margin-right: 8px;
  font-weight: 700;
}

.video-card .meta {
  color: #999;
  font-size: 14px;
  margin: 0 0 10px;
}

.video-card .desc {
  color: #666;
  font-size: 14px;
  line-height: 1.6;
  margin: 0;
}

.video-list {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.quick-links {
  background: white;
  padding: 30px;
  border-radius: 12px;
  box-shadow: 0 2px 12px rgba(0,0,0,0.08);
}

.link-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 20px;
}

.link-card {
  padding: 25px;
  background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
  border-radius: 10px;
  transition: all 0.3s ease;
  border: 2px solid transparent;
}

.link-card:hover {
  transform: translateY(-3px);
  border-color: #667eea;
  box-shadow: 0 5px 20px rgba(102, 126, 234, 0.2);
}

.link-card h3 {
  margin: 0 0 10px;
  font-size: 20px;
}

.link-card h3 a {
  color: #667eea;
  text-decoration: none;
  font-weight: 600;
}

.link-card p {
  margin: 0;
  color: #666;
  font-size: 14px;
  line-height: 1.6;
}

.more-link {
  text-align: center;
  margin-top: 30px;
}

.more-link a {
  display: inline-block;
  padding: 12px 30px;
  background: linear-gradient(135deg, #667eea, #764ba2);
  color: white;
  text-decoration: none;
  border-radius: 25px;
  font-weight: 600;
  transition: all 0.3s ease;
  box-shadow: 0 4px 15px rgba(102, 126, 234, 0.3);
}

.more-link a:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(102, 126, 234, 0.4);
}

.list-page {
  background: white;
  padding: 40px;
  border-radius: 12px;
  box-shadow: 0 2px 12px rgba(0,0,0,0.08);
}

.list-page h1 {
  font-size: 32px;
  color: #667eea;
  margin: 0 0 15px;
  font-weight: 700;
}

.list-page .page-desc {
  color: #666;
  font-size: 15px;
  margin: 0 0 30px;
  line-height: 1.7;
}

.detail-page {
  background: white;
  padding: 50px;
  border-radius: 12px;
  box-shadow: 0 2px 12px rgba(0,0,0,0.08);
}

.detail-page h1 {
  font-size: 36px;
  color: #2c3e50;
  margin: 0 0 30px;
  font-weight: 700;
  border-bottom: 3px solid #667eea;
  padding-bottom: 15px;
}

.detail-page h2 {
  font-size: 22px;
  color: #667eea;
  margin: 30px 0 15px;
  font-weight: 600;
}

.basic-info .info-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 12px;
}

.basic-info .info-list li {
  padding: 10px 15px;
  background: #f8f9fa;
  border-radius: 6px;
  border-left: 3px solid #667eea;
}

.highlight {
  background: linear-gradient(135deg, #667eea15, #764ba215);
  padding: 25px;
  border-radius: 10px;
  border-left: 4px solid #667eea;
  margin: 30px 0;
}

.one-line {
  font-size: 18px;
  color: #2c3e50;
  font-weight: 500;
  margin: 0;
  line-height: 1.6;
}

.content {
  color: #555;
  line-height: 1.9;
  font-size: 16px;
}

footer {
  background: #2c3e50;
  color: white;
  text-align: center;
  padding: 30px 20px;
  margin-top: 50px;
}

footer p {
  margin: 0;
  font-size: 14px;
}

@media (max-width: 768px) {
  .logo {
    font-size: 20px;
    padding: 15px 0 8px;
  }

  nav ul li a {
    padding: 12px 5px;
    font-size: 13px;
  }

  main {
    padding: 20px 15px;
  }

  .hero {
    padding: 30px 15px;
  }

  .hero h1 {
    font-size: 24px;
  }

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

  section h2 {
    font-size: 22px;
  }

  .video-grid {
    grid-template-columns: 1fr;
    gap: 15px;
  }

  .link-cards {
    grid-template-columns: 1fr;
  }

  .detail-page {
    padding: 25px 20px;
  }

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

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

  .list-page {
    padding: 25px 20px;
  }

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

@media (max-width: 480px) {
  nav ul li a {
    padding: 10px 3px;
    font-size: 12px;
  }

  .logo {
    font-size: 18px;
  }
}