/* 全局样式 */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Microsoft YaHei', sans-serif;
  line-height: 1.6;
  color: #333;
  background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
  min-height: 100vh;
}

/* 头部导航 */
.header {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
  padding: 1rem 1.5rem;
  box-shadow: 0 4px 12px rgba(0,0,0,0.15);
  position: sticky;
  top: 0;
  z-index: 1000;
}

.header-content {
  max-width: 1400px;
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 1rem;
}

.logo {
  font-size: 1.75rem;
  font-weight: 700;
  color: white;
  text-decoration: none;
  text-shadow: 2px 2px 4px rgba(0,0,0,0.2);
  transition: transform 0.3s;
}

.logo:hover {
  transform: scale(1.05);
}

.nav {
  display: flex;
  flex-wrap: nowrap;
  gap: 0.5rem;
  align-items: center;
}

.nav a {
  color: white;
  text-decoration: none;
  padding: 0.6rem 1.2rem;
  border-radius: 6px;
  transition: all 0.3s;
  white-space: nowrap;
  font-weight: 500;
  background: rgba(255,255,255,0.1);
}

.nav a:hover {
  background: rgba(255,255,255,0.25);
  transform: translateY(-2px);
  box-shadow: 0 4px 8px rgba(0,0,0,0.2);
}

/* 移动端导航 */
@media (max-width: 768px) {
  .header {
    padding: 1rem;
  }

  .header-content {
    flex-direction: column;
    gap: 1rem;
  }

  .logo {
    font-size: 1.4rem;
  }

  .nav {
    width: 100%;
    justify-content: space-between;
    gap: 0.25rem;
    flex-wrap: nowrap;
    overflow: visible;
  }

  .nav a {
    flex: 1 1 0;
    min-width: 0;
    text-align: center;
    padding: 0.5rem 0.2rem;
    font-size: 0.8rem;
    overflow: hidden;
    text-overflow: ellipsis;
    background: rgba(255,255,255,0.15);
  }
}

/* 容器 */
.container {
  max-width: 1400px;
  margin: 2.5rem auto;
  padding: 0 1.5rem;
}

/* 主内容区 */
.main-content {
  background: white;
  padding: 2.5rem;
  border-radius: 12px;
  box-shadow: 0 8px 24px rgba(0,0,0,0.1);
}

/* 标题样式 */
h1 {
  color: #2c3e50;
  margin-bottom: 2rem;
  font-size: 2rem;
  line-height: 1.4;
  border-bottom: 3px solid #667eea;
  padding-bottom: 1rem;
  font-weight: 700;
}

h2 {
  color: #34495e;
  margin: 2.5rem 0 1.5rem;
  font-size: 1.5rem;
  border-left: 5px solid #667eea;
  padding-left: 1.2rem;
  font-weight: 600;
}

h3 {
  font-size: 1.15rem;
  font-weight: 600;
}

/* 信息区块 */
.info-section {
  background: linear-gradient(135deg, #f8f9fa 0%, #e9ecef 100%);
  padding: 2rem;
  border-radius: 10px;
  margin: 2rem 0;
  border-left: 4px solid #667eea;
}

.info-section p {
  margin-bottom: 1rem;
  line-height: 1.9;
  font-size: 1rem;
}

.info-section p:last-child {
  margin-bottom: 0;
}

/* 视频网格 */
.video-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 2rem;
  margin: 2rem 0;
}

@media (max-width: 768px) {
  .video-grid {
    grid-template-columns: 1fr;
    gap: 1.5rem;
  }
}

/* 视频卡片 */
.video-card {
  background: #fff;
  border: 1px solid #e0e0e0;
  border-radius: 10px;
  padding: 1.75rem;
  transition: all 0.3s ease;
  position: relative;
  overflow: hidden;
}

.video-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 4px;
  background: linear-gradient(90deg, #667eea 0%, #764ba2 100%);
  transform: scaleX(0);
  transition: transform 0.3s ease;
}

.video-card:hover {
  box-shadow: 0 8px 20px rgba(102, 126, 234, 0.25);
  transform: translateY(-4px);
  border-color: #667eea;
}

.video-card:hover::before {
  transform: scaleX(1);
}

.video-card h3 {
  color: #2c3e50;
  margin-bottom: 0.75rem;
  font-size: 1.15rem;
  line-height: 1.4;
}

.video-card p {
  color: #666;
  font-size: 0.95rem;
  margin: 0.6rem 0;
  line-height: 1.6;
}

.video-card a {
  color: #667eea;
  text-decoration: none;
  font-weight: 600;
  transition: color 0.3s;
}

.video-card a:hover {
  color: #764ba2;
  text-decoration: underline;
}

/* 段落 */
p {
  margin-bottom: 1rem;
  line-height: 1.8;
}

/* 列表 */
ul {
  list-style: none;
}

li {
  padding: 0.6rem 0;
  line-height: 1.6;
}

/* 链接 */
a {
  color: #667eea;
  text-decoration: none;
  transition: color 0.3s;
}

a:hover {
  color: #764ba2;
  text-decoration: underline;
}

/* 页脚 */
.footer {
  text-align: center;
  padding: 2.5rem 1rem;
  color: #7f8c8d;
  margin-top: 4rem;
  background: rgba(255,255,255,0.8);
  border-radius: 12px;
  max-width: 1400px;
  margin-left: auto;
  margin-right: auto;
}

.footer p {
  margin: 0;
  font-size: 0.95rem;
}

/* UI样式变体 */
.ui-style-0 { --primary-color: #3498db; }
.ui-style-1 { --primary-color: #e74c3c; }
.ui-style-2 { --primary-color: #2ecc71; }
.ui-style-3 { --primary-color: #f39c12; }
.ui-style-4 { --primary-color: #9b59b6; }
.ui-style-5 { --primary-color: #667eea; }
.ui-style-6 { --primary-color: #16a085; }
.ui-style-7 { --primary-color: #d35400; }
.ui-style-8 { --primary-color: #c0392b; }
.ui-style-9 { --primary-color: #27ae60; }
.ui-style-10 { --primary-color: #2980b9; }
.ui-style-11 { --primary-color: #8e44ad; }
.ui-style-12 { --primary-color: #f1c40f; }
.ui-style-13 { --primary-color: #e67e22; }
.ui-style-14 { --primary-color: #1abc9c; }
.ui-style-15 { --primary-color: #34495e; }

/* 响应式优化 */
@media (max-width: 992px) {
  .main-content {
    padding: 2rem;
  }

  h1 {
    font-size: 1.6rem;
  }

  h2 {
    font-size: 1.3rem;
  }
}

@media (max-width: 576px) {
  .container {
    margin: 1.5rem auto;
    padding: 0 1rem;
  }

  .main-content {
    padding: 1.5rem;
  }

  h1 {
    font-size: 1.4rem;
  }

  h2 {
    font-size: 1.2rem;
    margin: 2rem 0 1rem;
  }

  .info-section {
    padding: 1.5rem;
  }

  .video-card {
    padding: 1.5rem;
  }
}