* { margin: 0; padding: 0; box-sizing: border-box; }
body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Microsoft YaHei', sans-serif;
  background: #f5f5f5;
  color: #333;
  line-height: 1.6;
}
.header {
  background: #fff;
  box-shadow: 0 2px 8px rgba(0,0,0,0.1);
  position: sticky;
  top: 0;
  z-index: 100;
}
.container { max-width: 1200px; margin: 0 auto; padding: 0 20px; }
.nav {
  display: flex;
  flex-wrap: nowrap;
  justify-content: space-between;
  align-items: center;
  padding: 15px 0;
}
.nav a {
  flex: 1 1 0;
  min-width: 0;
  text-align: center;
  color: #333;
  text-decoration: none;
  padding: 8px 5px;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  font-size: 14px;
  transition: color 0.3s;
}
.nav a:hover { color: #1890ff; }
.logo { font-size: 24px; font-weight: bold; color: #1890ff; padding: 10px 0; text-decoration: none; display: inline-block; }
a { color: #1890ff; text-decoration: none; }
a:hover { text-decoration: underline; }
ul { list-style: none; }

.main { padding: 30px 0; min-height: 60vh; }
.section {
  background: #fff;
  border-radius: 8px;
  padding: 30px;
  margin-bottom: 30px;
  box-shadow: 0 2px 12px rgba(0,0,0,0.08);
}
.section h1 {
  font-size: 28px;
  margin-bottom: 20px;
  color: #1890ff;
  border-left: 4px solid #1890ff;
  padding-left: 15px;
}
.section h2 {
  font-size: 24px;
  margin-bottom: 20px;
  color: #1890ff;
  border-left: 4px solid #1890ff;
  padding-left: 15px;
}
.section h3 {
  font-size: 20px;
  margin-bottom: 15px;
  color: #333;
}
.video-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 20px;
}
.video-card {
  background: #fafafa;
  border-radius: 6px;
  padding: 20px;
  transition: transform 0.3s, box-shadow 0.3s;
  border: 1px solid #eee;
}
.video-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 4px 16px rgba(0,0,0,0.12);
}
.video-card h3 {
  font-size: 18px;
  margin-bottom: 10px;
  color: #333;
}
.video-card .meta {
  font-size: 13px;
  color: #666;
  margin: 5px 0;
}
.video-card .tags {
  margin: 10px 0;
}
.video-card .tags span {
  display: inline-block;
  background: #e6f7ff;
  color: #1890ff;
  padding: 2px 8px;
  border-radius: 3px;
  font-size: 12px;
  margin-right: 5px;
  margin-bottom: 5px;
}
.video-card .desc {
  font-size: 14px;
  color: #666;
  line-height: 1.6;
  margin-top: 10px;
}
.intro {
  font-size: 15px;
  line-height: 1.8;
  color: #555;
  margin-bottom: 20px;
  text-indent: 2em;
}
.detail-info {
  background: #fafafa;
  padding: 20px;
  border-radius: 6px;
  margin-bottom: 20px;
  border: 1px solid #eee;
}
.detail-info .item {
  margin: 10px 0;
  font-size: 15px;
}
.detail-info .item strong {
  color: #333;
  min-width: 80px;
  display: inline-block;
}
.summary {
  font-size: 15px;
  line-height: 1.8;
  color: #555;
  margin: 20px 0;
  text-indent: 2em;
}
.review {
  background: #fff9e6;
  border-left: 4px solid #faad14;
  padding: 15px 20px;
  margin: 20px 0;
  border-radius: 4px;
}
.review h3 {
  color: #d48806;
  font-size: 16px;
  margin-bottom: 10px;
}
.review p {
  color: #555;
  line-height: 1.8;
}
.footer {
  background: #fff;
  text-align: center;
  padding: 30px 20px;
  color: #999;
  margin-top: 50px;
  box-shadow: 0 -2px 8px rgba(0,0,0,0.05);
  font-size: 14px;
}
.list-item {
  background: #fafafa;
  padding: 20px;
  margin-bottom: 15px;
  border-radius: 6px;
  border: 1px solid #eee;
  transition: transform 0.2s, box-shadow 0.2s;
}
.list-item:hover {
  transform: translateX(5px);
  box-shadow: 0 2px 12px rgba(0,0,0,0.1);
}
.list-item h3 {
  font-size: 18px;
  color: #333;
  margin-bottom: 10px;
}
.list-item .meta {
  font-size: 13px;
  color: #999;
  margin: 5px 0;
}
.list-item .desc {
  font-size: 14px;
  color: #666;
  line-height: 1.6;
  margin-top: 10px;
}

@media (max-width: 768px) {
  .nav a { font-size: 12px; padding: 8px 3px; }
  .container { padding: 0 15px; }
  .video-grid { grid-template-columns: 1fr; }
  .section { padding: 20px 15px; }
  .section h1 { font-size: 24px; }
  .section h2 { font-size: 20px; }
  .logo { font-size: 20px; }
}