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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  line-height: 1.6;
  color: #333;
  background: #f5f5f5;
}

a {
  text-decoration: none;
  color: #0066cc;
  transition: color 0.3s;
}

a:hover {
  color: #004499;
}

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

header {
  background: #fff;
  box-shadow: 0 2px 4px rgba(0,0,0,0.1);
  position: sticky;
  top: 0;
  z-index: 1000;
}

.header-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 15px 20px;
  max-width: 1200px;
  margin: 0 auto;
}

.logo {
  font-size: 24px;
  font-weight: bold;
  color: #333;
}

nav {
  display: flex;
  flex-wrap: nowrap;
  align-items: center;
  justify-content: space-between;
  flex: 1;
  max-width: 600px;
  margin-left: 40px;
}

nav a {
  padding: 8px 15px;
  border-radius: 4px;
  white-space: nowrap;
  flex: 1 1 0;
  min-width: 0;
  text-align: center;
  overflow: hidden;
  text-overflow: ellipsis;
}

nav a:hover {
  background: #f0f0f0;
}

main {
  padding: 40px 0;
}

section {
  background: #fff;
  padding: 30px;
  margin-bottom: 30px;
  border-radius: 8px;
  box-shadow: 0 2px 8px rgba(0,0,0,0.05);
}

h1 {
  font-size: 32px;
  margin-bottom: 20px;
  line-height: 1.2;
  color: #222;
}

h2 {
  font-size: 24px;
  margin-bottom: 15px;
  color: #333;
  border-left: 4px solid #0066cc;
  padding-left: 15px;
}

h3 {
  font-size: 20px;
  margin-bottom: 12px;
  color: #444;
}

.intro-text {
  font-size: 16px;
  line-height: 1.8;
  color: #555;
  margin-bottom: 20px;
}

.video-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 20px;
  margin-top: 20px;
}

.video-card {
  background: #fff;
  border: 1px solid #e0e0e0;
  border-radius: 6px;
  padding: 20px;
  transition: transform 0.3s, box-shadow 0.3s;
}

.video-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 4px 12px rgba(0,0,0,0.15);
}

.video-title {
  font-size: 18px;
  font-weight: bold;
  margin-bottom: 10px;
  color: #222;
}

.video-meta {
  font-size: 14px;
  color: #666;
  margin-bottom: 8px;
}

.video-oneline {
  font-size: 14px;
  color: #777;
  line-height: 1.5;
  margin-top: 10px;
}

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

.video-list li {
  padding: 15px 0;
  border-bottom: 1px solid #e0e0e0;
}

.video-list li:last-child {
  border-bottom: none;
}

.info-grid {
  display: grid;
  grid-template-columns: 120px 1fr;
  gap: 10px;
  margin-bottom: 15px;
  font-size: 15px;
}

.info-label {
  font-weight: bold;
  color: #555;
}

.info-value {
  color: #333;
}

.summary-text {
  font-size: 15px;
  line-height: 1.8;
  color: #555;
  margin-bottom: 20px;
  text-indent: 2em;
}

.review-box {
  background: #f9f9f9;
  padding: 20px;
  border-left: 4px solid #0066cc;
  border-radius: 4px;
  margin-bottom: 20px;
}

.review-text {
  font-size: 15px;
  line-height: 1.7;
  color: #444;
  font-style: italic;
}

.related-section {
  margin-top: 40px;
}

.related-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: 15px;
  margin-top: 20px;
}

.related-card {
  background: #f9f9f9;
  padding: 15px;
  border-radius: 6px;
  border: 1px solid #e0e0e0;
}

.related-card h4 {
  font-size: 16px;
  margin-bottom: 8px;
  color: #333;
}

.related-card p {
  font-size: 14px;
  color: #666;
  line-height: 1.5;
}

footer {
  background: #333;
  color: #fff;
  text-align: center;
  padding: 20px;
  margin-top: 40px;
}

@media (max-width: 768px) {
  .header-inner {
    flex-direction: column;
    align-items: flex-start;
  }

  nav {
    margin-left: 0;
    margin-top: 10px;
    width: 100%;
    max-width: 100%;
    font-size: 14px;
  }

  nav a {
    padding: 6px 8px;
    font-size: 13px;
  }

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

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

  h1 {
    font-size: 24px;
  }

  h2 {
    font-size: 20px;
  }
}