body {
  font-size: 16px;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

main {
  flex: 1;
  max-width: 1200px;
  width: 100%;
  margin: 0 auto;
  padding: 2rem 1rem;
}

footer {
  background: #2c3e50;
  color: white;
  text-align: center;
  padding: 1.5rem 1rem;
  margin-top: 3rem;
}

.site-header, .page-header {
  text-align: center;
  margin-bottom: 2rem;
  padding-bottom: 1rem;
  border-bottom: 2px solid #3498db;
}

.site-header h1, .page-header h1 {
  font-size: 2rem;
  color: #2c3e50;
  margin-bottom: 0.5rem;
}

.page-header p {
  color: #7f8c8d;
  font-size: 1rem;
}

.site-intro {
  background: white;
  padding: 1.5rem;
  border-radius: 8px;
  margin-bottom: 2rem;
  box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

.site-intro p {
  line-height: 1.8;
  color: #555;
}

section {
  margin-bottom: 3rem;
}

section h2 {
  font-size: 1.5rem;
  color: #2c3e50;
  margin-bottom: 1rem;
  padding-bottom: 0.5rem;
  border-bottom: 2px solid #ecf0f1;
}

.video-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1.5rem;
}

.video-card {
  background: white;
  padding: 1.5rem;
  border-radius: 8px;
  box-shadow: 0 2px 4px rgba(0,0,0,0.1);
  transition: transform 0.3s, box-shadow 0.3s;
}

.video-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 4px 12px rgba(0,0,0,0.15);
}

.video-card h3, .video-card h4 {
  margin-bottom: 0.5rem;
}

.video-card h3 a, .video-card h4 a {
  color: #2c3e50;
  text-decoration: none;
  font-size: 1.1rem;
}

.video-card h3 a:hover, .video-card h4 a:hover {
  color: #3498db;
}

.video-card .meta {
  color: #7f8c8d;
  font-size: 0.9rem;
  margin-bottom: 0.5rem;
}

.video-card .desc {
  color: #555;
  font-size: 0.95rem;
  line-height: 1.6;
}

.video-list {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.video-item {
  background: white;
  padding: 1rem 1.5rem;
  border-radius: 8px;
  box-shadow: 0 2px 4px rgba(0,0,0,0.1);
  transition: box-shadow 0.3s;
}

.video-item:hover {
  box-shadow: 0 4px 8px rgba(0,0,0,0.15);
}

.video-item h3 {
  margin-bottom: 0.3rem;
}

.video-item h3 a {
  color: #2c3e50;
  text-decoration: none;
  font-size: 1.1rem;
}

.video-item h3 a:hover {
  color: #3498db;
}

.video-item p {
  color: #666;
  font-size: 0.9rem;
}

.link-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 1.5rem;
}

.link-card {
  background: white;
  padding: 2rem;
  border-radius: 8px;
  box-shadow: 0 2px 4px rgba(0,0,0,0.1);
  text-align: center;
  transition: transform 0.3s;
}

.link-card:hover {
  transform: scale(1.05);
}

.link-card h3 a {
  color: #2c3e50;
  text-decoration: none;
  font-size: 1.3rem;
}

.link-card h3 a:hover {
  color: #3498db;
}

.link-card p {
  color: #7f8c8d;
  margin-top: 0.5rem;
}

.more-link {
  text-align: center;
  margin-top: 1.5rem;
}

.more-link a {
  color: #3498db;
  text-decoration: none;
  font-size: 1rem;
  padding: 0.5rem 1.5rem;
  border: 2px solid #3498db;
  border-radius: 4px;
  display: inline-block;
  transition: all 0.3s;
}

.more-link a:hover {
  background: #3498db;
  color: white;
}

.list-item {
  background: white;
  padding: 1.5rem;
  border-radius: 8px;
  box-shadow: 0 2px 4px rgba(0,0,0,0.1);
  margin-bottom: 1rem;
}

.list-item h3 a {
  color: #2c3e50;
  text-decoration: none;
  font-size: 1.2rem;
}

.list-item h3 a:hover {
  color: #3498db;
}

.list-item .meta {
  color: #7f8c8d;
  font-size: 0.9rem;
  margin: 0.5rem 0;
}

.list-item .desc {
  color: #555;
  line-height: 1.6;
}

.rank-item {
  display: flex;
  gap: 1rem;
  align-items: flex-start;
}

.rank-num {
  font-size: 2rem;
  font-weight: bold;
  color: #3498db;
  min-width: 50px;
  text-align: center;
}

.topic-group {
  margin-bottom: 2.5rem;
}

.group-title {
  font-size: 1.3rem;
  color: #34495e;
  margin-bottom: 1rem;
  padding-left: 1rem;
  border-left: 4px solid #3498db;
}

.detail-page {
  background: white;
  padding: 2rem;
  border-radius: 8px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.1);
}

.detail-page header h1 {
  font-size: 2rem;
  color: #2c3e50;
  margin-bottom: 1.5rem;
  padding-bottom: 1rem;
  border-bottom: 2px solid #ecf0f1;
}

.detail-info dl {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 0.8rem 1.5rem;
  margin-bottom: 2rem;
}

.detail-info dt {
  font-weight: bold;
  color: #34495e;
}

.detail-info dd {
  color: #555;
}

.detail-oneline, .detail-summary, .detail-review {
  margin-bottom: 2rem;
}

.detail-oneline h2, .detail-summary h2, .detail-review h2, .detail-related h2 {
  font-size: 1.3rem;
  color: #2c3e50;
  margin-bottom: 1rem;
}

.detail-oneline p, .detail-summary p, .detail-review p {
  color: #555;
  line-height: 1.8;
  font-size: 1rem;
}

.detail-related {
  margin-top: 3rem;
  padding-top: 2rem;
  border-top: 2px solid #ecf0f1;
}

@media (max-width: 768px) {
  .site-header h1, .page-header h1 {
    font-size: 1.5rem;
  }

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

  .detail-info dl {
    grid-template-columns: 1fr;
    gap: 0.5rem;
  }

  main {
    padding: 1rem 0.5rem;
  }

  .detail-page {
    padding: 1rem;
  }
}