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

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue', sans-serif;
  line-height: 1.6;
  color: #333;
  background-color: #f8f9fa;
  overflow-x: hidden;
}

/* ==================== 颜色变量 ==================== */
:root {
  --primary-teal: #0d9488;
  --primary-coral: #f97316;
  --dark-bg: #0f172a;
  --light-bg: #f8fafc;
  --text-dark: #1e293b;
  --text-light: #64748b;
  --border-color: #e2e8f0;
  --shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 25px rgba(0, 0, 0, 0.15);
}

/* ==================== 导航栏 ==================== */
header {
  background: linear-gradient(135deg, var(--dark-bg) 0%, #1a2a4a 100%);
  color: white;
  position: sticky;
  top: 0;
  z-index: 1000;
  box-shadow: var(--shadow-lg);
}

.navbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0.75rem 2rem;
  max-width: 1400px;
  margin: 0 auto;
}

.logo-section {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.logo-img {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  object-fit: cover;
  border: 2px solid var(--primary-coral);
}

.brand-name {
  font-size: 1.5rem;
  font-weight: 700;
  background: linear-gradient(135deg, var(--primary-teal), var(--primary-coral));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.nav-menu {
  display: flex;
  list-style: none;
  gap: 0;
  align-items: center;
}

.nav-item {
  position: relative;
}

.nav-link {
  display: block;
  color: white;
  text-decoration: none;
  padding: 0.75rem 1.25rem;
  transition: all 0.3s ease;
  font-weight: 500;
  font-size: 0.95rem;
}

.nav-link:hover {
  color: var(--primary-coral);
  background-color: rgba(249, 115, 22, 0.1);
}

.search-container {
  display: flex;
  align-items: center;
  background-color: rgba(255, 255, 255, 0.1);
  border-radius: 25px;
  padding: 0.5rem 1rem;
  margin-left: 1rem;
}

.search-input {
  background: none;
  border: none;
  color: white;
  outline: none;
  width: 200px;
  font-size: 0.9rem;
}

.search-input::placeholder {
  color: rgba(255, 255, 255, 0.6);
}

.search-btn {
  background: none;
  border: none;
  color: white;
  cursor: pointer;
  font-size: 1rem;
  padding: 0 0.5rem;
}

/* ==================== 英雄区域 ==================== */
.hero {
  position: relative;
  height: 500px;
  background: linear-gradient(135deg, var(--dark-bg) 0%, #1a2a4a 50%, var(--primary-teal) 100%);
  overflow: hidden;
  display: flex;
  align-items: center;
  justify-content: center;
}

.hero-bg {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  opacity: 0.6;
  z-index: 1;
}

.hero-content {
  position: relative;
  z-index: 2;
  text-align: center;
  color: white;
  max-width: 800px;
  padding: 2rem;
}

.hero-title {
  font-size: 3rem;
  font-weight: 800;
  margin-bottom: 1rem;
  text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.3);
}

.hero-subtitle {
  font-size: 1.3rem;
  margin-bottom: 2rem;
  color: rgba(255, 255, 255, 0.9);
  text-shadow: 1px 1px 2px rgba(0, 0, 0, 0.3);
}

.hero-cta {
  display: inline-flex;
  gap: 1rem;
}

.btn {
  padding: 0.75rem 2rem;
  border: none;
  border-radius: 50px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.3s ease;
  text-decoration: none;
  display: inline-block;
}

.btn-primary {
  background: linear-gradient(135deg, var(--primary-coral), #ea580c);
  color: white;
  box-shadow: 0 4px 15px rgba(249, 115, 22, 0.4);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(249, 115, 22, 0.6);
}

.btn-secondary {
  background: rgba(255, 255, 255, 0.2);
  color: white;
  border: 2px solid white;
}

.btn-secondary:hover {
  background: white;
  color: var(--primary-teal);
}

/* ==================== 内容区域 ==================== */
.container {
  max-width: 1400px;
  margin: 0 auto;
  padding: 0 2rem;
}

.section {
  padding: 4rem 0;
}

.section-title {
  font-size: 2.5rem;
  font-weight: 800;
  text-align: center;
  margin-bottom: 3rem;
  color: var(--text-dark);
  position: relative;
  padding-bottom: 1rem;
}

.section-title::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 60px;
  height: 4px;
  background: linear-gradient(90deg, var(--primary-teal), var(--primary-coral));
  border-radius: 2px;
}

/* ==================== 视频卡片 ==================== */
.video-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 2rem;
  margin-bottom: 3rem;
}

.video-card {
  background: white;
  border-radius: 12px;
  overflow: hidden;
  box-shadow: var(--shadow);
  transition: all 0.3s ease;
  cursor: pointer;
  position: relative;
}

.video-card:hover {
  transform: translateY(-8px);
  box-shadow: var(--shadow-lg);
}

.video-thumb {
  position: relative;
  width: 100%;
  padding-bottom: 56.25%;
  background: linear-gradient(135deg, var(--primary-teal), var(--primary-coral));
  overflow: hidden;
}

.video-thumb img {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  opacity: 1;
  transition: opacity 0.3s ease;
}

.video-card:hover .video-thumb img {
  opacity: 1;
}

.play-btn {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 60px;
  height: 60px;
  background: rgba(249, 115, 22, 0.9);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  color: white;
  opacity: 0;
  transition: all 0.3s ease;
  z-index: 10;
}

.video-card:hover .play-btn {
  opacity: 1;
  transform: translate(-50%, -50%) scale(1.1);
}

.video-info {
  padding: 1.5rem;
}

.video-title {
  font-size: 1.1rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
  color: var(--text-dark);
  line-height: 1.4;
}

.video-desc {
  font-size: 0.9rem;
  color: var(--text-light);
  margin-bottom: 1rem;
  line-height: 1.5;
}

.video-stats {
  display: flex;
  gap: 1.5rem;
  font-size: 0.85rem;
  color: var(--text-light);
}

.stat-item {
  display: flex;
  align-items: center;
  gap: 0.3rem;
}

/* ==================== 特色模块 ==================== */
.feature-section {
  background: linear-gradient(135deg, var(--dark-bg), #1a2a4a);
  color: white;
  padding: 4rem 0;
}

.feature-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 2rem;
}

.feature-card {
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid rgba(255, 255, 255, 0.1);
  padding: 2rem;
  border-radius: 12px;
  transition: all 0.3s ease;
  text-align: center;
}

.feature-card:hover {
  background: rgba(255, 255, 255, 0.1);
  border-color: var(--primary-coral);
  transform: translateY(-5px);
}

.feature-icon {
  font-size: 3rem;
  margin-bottom: 1rem;
}

.feature-title {
  font-size: 1.3rem;
  font-weight: 700;
  margin-bottom: 1rem;
}

.feature-desc {
  font-size: 0.95rem;
  line-height: 1.6;
  color: rgba(255, 255, 255, 0.8);
}

/* ==================== 专家展示 ==================== */
.expert-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 2rem;
}

.expert-card {
  background: white;
  border-radius: 12px;
  overflow: hidden;
  box-shadow: var(--shadow);
  transition: all 0.3s ease;
  text-align: center;
}

.expert-card:hover {
  transform: translateY(-8px);
  box-shadow: var(--shadow-lg);
}

.expert-card img {
  width: 100%;
  height: 250px;
  object-fit: cover;
  background: linear-gradient(135deg, var(--primary-teal), var(--primary-coral));
  display: block;
}

.expert-img {
  width: 100%;
  height: 250px;
  object-fit: cover;
  background: linear-gradient(135deg, var(--primary-teal), var(--primary-coral));
}

.expert-info {
  padding: 1.5rem;
}

.expert-name {
  font-size: 1.2rem;
  font-weight: 700;
  margin-bottom: 0.3rem;
  color: var(--text-dark);
}

.expert-title {
  font-size: 0.9rem;
  color: var(--primary-coral);
  font-weight: 600;
  margin-bottom: 1rem;
}

.expert-desc {
  font-size: 0.85rem;
  color: var(--text-light);
  margin-bottom: 1rem;
  line-height: 1.5;
}

.expert-actions {
  display: flex;
  gap: 0.5rem;
  justify-content: center;
}

.expert-btn {
  padding: 0.5rem 1rem;
  background: linear-gradient(135deg, var(--primary-teal), var(--primary-coral));
  color: white;
  border: none;
  border-radius: 20px;
  font-size: 0.8rem;
  cursor: pointer;
  transition: all 0.3s ease;
  text-decoration: none;
  display: inline-block;
}

.expert-btn:hover {
  transform: scale(1.05);
  box-shadow: 0 4px 12px rgba(249, 115, 22, 0.3);
}

/* ==================== 社区评论 ==================== */
.comment-section {
  background: white;
  padding: 2rem;
  border-radius: 12px;
  margin-bottom: 2rem;
  box-shadow: var(--shadow);
}

.comment-header {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 1rem;
}

.comment-avatar {
  width: 50px;
  height: 50px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--primary-teal), var(--primary-coral));
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-weight: 700;
  font-size: 1.2rem;
}

.comment-meta {
  flex: 1;
}

.comment-name {
  font-weight: 700;
  color: var(--text-dark);
  margin-bottom: 0.2rem;
}

.comment-time {
  font-size: 0.8rem;
  color: var(--text-light);
}

.comment-text {
  color: var(--text-dark);
  line-height: 1.6;
  margin-bottom: 1rem;
}

.comment-rating {
  color: var(--primary-coral);
  font-size: 1rem;
}

/* ==================== FAQ ==================== */
.faq-item {
  background: white;
  border-radius: 12px;
  margin-bottom: 1rem;
  box-shadow: var(--shadow);
  overflow: hidden;
}

.faq-question {
  padding: 1.5rem;
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-weight: 600;
  color: var(--text-dark);
  transition: all 0.3s ease;
  background: white;
}

.faq-question:hover {
  background: linear-gradient(135deg, rgba(13, 148, 136, 0.05), rgba(249, 115, 22, 0.05));
}

.faq-icon {
  font-size: 1.2rem;
  transition: transform 0.3s ease;
  color: var(--primary-coral);
}

.faq-item.active .faq-icon {
  transform: rotate(180deg);
}

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.3s ease;
  background: linear-gradient(135deg, rgba(13, 148, 136, 0.05), rgba(249, 115, 22, 0.05));
}

.faq-item.active .faq-answer {
  max-height: 500px;
  padding: 1.5rem;
  border-top: 2px solid var(--border-color);
}

.faq-answer p {
  color: var(--text-light);
  line-height: 1.6;
}

/* ==================== 联系我们 ==================== */
.contact-section {
  background: linear-gradient(135deg, var(--dark-bg), #1a2a4a);
  color: white;
  padding: 4rem 0;
}

.contact-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 2rem;
}

.contact-card {
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid rgba(255, 255, 255, 0.1);
  padding: 2rem;
  border-radius: 12px;
  text-align: center;
  transition: all 0.3s ease;
}

.contact-card:hover {
  background: rgba(255, 255, 255, 0.1);
  border-color: var(--primary-coral);
}

.contact-icon {
  font-size: 2.5rem;
  margin-bottom: 1rem;
  color: var(--primary-coral);
}

.contact-title {
  font-size: 1.2rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
}

.contact-info {
  font-size: 0.95rem;
  color: rgba(255, 255, 255, 0.8);
  line-height: 1.6;
}

.contact-link {
  color: var(--primary-coral);
  text-decoration: none;
  transition: all 0.3s ease;
}

.contact-link:hover {
  text-decoration: underline;
}

/* ==================== 页脚 ==================== */
footer {
  background: var(--dark-bg);
  color: white;
  padding: 3rem 0 1rem;
  border-top: 2px solid rgba(249, 115, 22, 0.3);
}

.footer-content {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 2rem;
  margin-bottom: 2rem;
}

.footer-section h3 {
  font-size: 1.1rem;
  font-weight: 700;
  margin-bottom: 1rem;
  color: var(--primary-coral);
}

.footer-section ul {
  list-style: none;
}

.footer-section li {
  margin-bottom: 0.5rem;
}

.footer-section a {
  color: rgba(255, 255, 255, 0.7);
  text-decoration: none;
  transition: all 0.3s ease;
  font-size: 0.9rem;
}

.footer-section a:hover {
  color: var(--primary-coral);
  padding-left: 0.5rem;
}

.footer-qr {
  text-align: center;
  margin-bottom: 2rem;
}

.qr-code {
  display: inline-block;
  background: white;
  padding: 1rem;
  border-radius: 8px;
  margin: 0.5rem;
}

.qr-code img {
  width: 120px;
  height: 120px;
}

.qr-label {
  font-size: 0.8rem;
  color: rgba(255, 255, 255, 0.7);
  margin-top: 0.5rem;
}

.footer-bottom {
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  padding-top: 2rem;
  text-align: center;
  color: rgba(255, 255, 255, 0.6);
  font-size: 0.9rem;
}

.footer-links {
  display: flex;
  justify-content: center;
  gap: 2rem;
  margin-bottom: 1rem;
  flex-wrap: wrap;
}

.footer-links a {
  color: rgba(255, 255, 255, 0.6);
  text-decoration: none;
  transition: all 0.3s ease;
}

.footer-links a:hover {
  color: var(--primary-coral);
}

/* ==================== 响应式设计 ==================== */
@media (max-width: 768px) {
  .navbar {
    flex-direction: column;
    gap: 1rem;
    padding: 1rem;
  }

  .nav-menu {
    flex-wrap: wrap;
    justify-content: center;
    gap: 0.5rem;
  }

  .nav-link {
    padding: 0.5rem 0.75rem;
    font-size: 0.85rem;
  }

  .search-container {
    width: 100%;
    margin-left: 0;
  }

  .search-input {
    width: 100%;
  }

  .hero {
    height: 350px;
  }

  .hero-title {
    font-size: 2rem;
  }

  .hero-subtitle {
    font-size: 1rem;
  }

  .hero-cta {
    flex-direction: column;
    gap: 0.5rem;
  }

  .btn {
    width: 100%;
    text-align: center;
  }

  .section-title {
    font-size: 1.8rem;
  }

  .video-grid {
    grid-template-columns: 1fr;
    gap: 1.5rem;
  }

  .feature-grid,
  .expert-grid,
  .contact-grid {
    grid-template-columns: 1fr;
  }

  .container {
    padding: 0 1rem;
  }

  .section {
    padding: 2rem 0;
  }
}

@media (max-width: 480px) {
  .brand-name {
    font-size: 1.2rem;
  }

  .hero-title {
    font-size: 1.5rem;
  }

  .hero-subtitle {
    font-size: 0.9rem;
  }

  .section-title {
    font-size: 1.5rem;
  }

  .video-title {
    font-size: 1rem;
  }

  .video-desc {
    font-size: 0.8rem;
  }

  .video-stats {
    font-size: 0.75rem;
  }
}

/* ==================== 懒加载与性能 ==================== */
img {
  loading: lazy;
}

.video-card img {
  will-change: opacity;
}

/* ==================== 打印样式 ==================== */
@media print {
  header,
  footer {
    display: none;
  }

  body {
    background: white;
  }
}