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

:root {
  --primary-color: #2c3e50;
  --secondary-color: #3498db;
  --accent-color: #e74c3c;
  --text-color: #333;
  --text-light: #666;
  --bg-light: #f8f9fa;
  --bg-dark: #1a1a1a;
  --border-color: #e0e0e0;
  --shadow: 0 2px 10px rgba(0,0,0,0.1);
  --shadow-hover: 0 4px 20px rgba(0,0,0,0.15);
  --transition: all 0.3s ease;
}

body {
  font-family: "Microsoft YaHei", "PingFang SC", "Helvetica Neue", Arial, sans-serif;
  color: var(--text-color);
  line-height: 1.6;
  background-color: #fff;
}

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

/* 导航栏 */
.navbar {
  background: var(--primary-color);
  color: #fff;
  padding: 1rem 0;
  position: sticky;
  top: 0;
  z-index: 1000;
  box-shadow: var(--shadow);
}

.navbar .container {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 1.5rem;
  font-weight: bold;
}

.logo i {
  font-size: 2rem;
  color: var(--secondary-color);
}

.nav-menu {
  display: flex;
  list-style: none;
  gap: 2rem;
}

.nav-menu a {
  color: #fff;
  text-decoration: none;
  transition: var(--transition);
  padding: 0.5rem 1rem;
  border-radius: 5px;
}

.nav-menu a:hover,
.nav-menu a.active {
  background: var(--secondary-color);
  color: #fff;
}

.hamburger {
  display: none;
  flex-direction: column;
  cursor: pointer;
  gap: 5px;
}

.hamburger span {
  width: 25px;
  height: 3px;
  background: #fff;
  transition: var(--transition);
}

/* 英雄区域 */
.hero {
  position: relative;
  height: 600px;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  color: #fff;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: url('https://images.unsplash.com/photo-1518709268805-4e9042af2176?w=1920') center/cover;
  opacity: 0.3;
  z-index: 1;
}

.hero-content {
  position: relative;
  z-index: 2;
  max-width: 800px;
  padding: 0 20px;
}

.hero-title {
  font-size: 3.5rem;
  margin-bottom: 1rem;
  text-shadow: 2px 2px 4px rgba(0,0,0,0.3);
  animation: fadeInUp 1s ease;
}

.hero-subtitle {
  font-size: 1.5rem;
  margin-bottom: 2rem;
  opacity: 0.9;
  animation: fadeInUp 1s ease 0.2s both;
}

.hero-buttons {
  display: flex;
  gap: 1rem;
  justify-content: center;
  flex-wrap: wrap;
  animation: fadeInUp 1s ease 0.4s both;
}

.hero-overlay {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: linear-gradient(135deg, rgba(102,126,234,0.8) 0%, rgba(118,75,162,0.8) 100%);
  z-index: 1;
}

/* 按钮样式 */
.btn {
  display: inline-block;
  padding: 12px 30px;
  border-radius: 5px;
  text-decoration: none;
  font-weight: bold;
  transition: var(--transition);
  border: none;
  cursor: pointer;
  font-size: 1rem;
}

.btn-primary {
  background: var(--secondary-color);
  color: #fff;
}

.btn-primary:hover {
  background: #2980b9;
  transform: translateY(-2px);
  box-shadow: var(--shadow-hover);
}

.btn-secondary {
  background: transparent;
  color: #fff;
  border: 2px solid #fff;
}

.btn-secondary:hover {
  background: #fff;
  color: var(--primary-color);
}

/* 章节标题 */
.section-header {
  text-align: center;
  margin-bottom: 3rem;
}

.section-header h2 {
  font-size: 2.5rem;
  margin-bottom: 1rem;
  color: var(--primary-color);
}

.section-subtitle {
  font-size: 1.1rem;
  color: var(--text-light);
  max-width: 700px;
  margin: 0 auto;
}

/* 介绍区域 */
.intro-section {
  padding: 5rem 0;
  background: var(--bg-light);
}

.intro-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 2rem;
}

.intro-card {
  background: #fff;
  padding: 2rem;
  border-radius: 10px;
  text-align: center;
  box-shadow: var(--shadow);
  transition: var(--transition);
}

.intro-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-hover);
}

.intro-icon {
  width: 80px;
  height: 80px;
  margin: 0 auto 1.5rem;
  background: linear-gradient(135deg, var(--secondary-color), #764ba2);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 2rem;
  color: #fff;
}

.intro-card h3 {
  font-size: 1.5rem;
  margin-bottom: 1rem;
  color: var(--primary-color);
}

/* 时间轴地图区域 */
.timeline-section {
  padding: 5rem 0;
  background: #fff;
}

.timeline-map-container {
  margin-top: 3rem;
}

.timeline-map {
  position: relative;
  width: 100%;
  height: 500px;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  border-radius: 10px;
  overflow: hidden;
  margin-bottom: 2rem;
  background-image: url('https://images.unsplash.com/photo-1524661135-423995f22d0b?w=1200');
  background-size: cover;
  background-position: center;
}

.map-marker {
  position: absolute;
  cursor: pointer;
  z-index: 10;
}

.marker-dot {
  width: 20px;
  height: 20px;
  background: var(--accent-color);
  border: 3px solid #fff;
  border-radius: 50%;
  box-shadow: 0 0 10px rgba(0,0,0,0.3);
  animation: pulse 2s infinite;
}

.marker-popup {
  position: absolute;
  bottom: 30px;
  left: 50%;
  transform: translateX(-50%);
  background: #fff;
  padding: 1rem;
  border-radius: 5px;
  box-shadow: var(--shadow-hover);
  min-width: 200px;
  opacity: 0;
  pointer-events: none;
  transition: var(--transition);
}

.map-marker:hover .marker-popup {
  opacity: 1;
  pointer-events: auto;
}

.marker-popup h4 {
  color: var(--primary-color);
  margin-bottom: 0.5rem;
}

.marker-popup p {
  font-size: 0.9rem;
  color: var(--text-light);
  margin: 0.25rem 0;
}

.timeline-controls {
  display: flex;
  justify-content: center;
  gap: 1rem;
  flex-wrap: wrap;
}

.timeline-btn {
  padding: 10px 20px;
  background: var(--bg-light);
  border: 2px solid var(--border-color);
  border-radius: 5px;
  cursor: pointer;
  transition: var(--transition);
  font-size: 1rem;
}

.timeline-btn:hover,
.timeline-btn.active {
  background: var(--secondary-color);
  color: #fff;
  border-color: var(--secondary-color);
}

/* 焦点文明区域 */
.featured-section {
  padding: 5rem 0;
  background: var(--bg-light);
}

.featured-card {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
  background: #fff;
  border-radius: 10px;
  overflow: hidden;
  box-shadow: var(--shadow);
}

.featured-image {
  position: relative;
  overflow: hidden;
}

.featured-image img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: var(--transition);
}

.featured-card:hover .featured-image img {
  transform: scale(1.1);
}

.featured-content {
  padding: 2rem;
  display: flex;
  flex-direction: column;
  justify-content: center;
}

.featured-badge {
  display: inline-block;
  background: var(--accent-color);
  color: #fff;
  padding: 0.5rem 1rem;
  border-radius: 20px;
  font-size: 0.9rem;
  margin-bottom: 1rem;
  width: fit-content;
}

.featured-content h3 {
  font-size: 2rem;
  margin-bottom: 1rem;
  color: var(--primary-color);
}

.featured-date {
  color: var(--text-light);
  margin-bottom: 1rem;
}

.featured-stats {
  display: flex;
  gap: 2rem;
  margin: 2rem 0;
}

.stat-item {
  text-align: center;
}

.stat-value {
  display: block;
  font-size: 2rem;
  font-weight: bold;
  color: var(--secondary-color);
}

.stat-label {
  display: block;
  font-size: 0.9rem;
  color: var(--text-light);
}

/* 问答区域 */
.qa-section {
  padding: 5rem 0;
  background: #fff;
}

.qa-container {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
}

.qa-form {
  background: var(--bg-light);
  padding: 2rem;
  border-radius: 10px;
}

.qa-form h3 {
  margin-bottom: 1.5rem;
  color: var(--primary-color);
}

.form-group {
  margin-bottom: 1.5rem;
}

.form-group label {
  display: block;
  margin-bottom: 0.5rem;
  color: var(--text-color);
  font-weight: bold;
}

.form-group input,
.form-group textarea {
  width: 100%;
  padding: 0.75rem;
  border: 2px solid var(--border-color);
  border-radius: 5px;
  font-family: inherit;
  font-size: 1rem;
  transition: var(--transition);
}

.form-group input:focus,
.form-group textarea:focus {
  outline: none;
  border-color: var(--secondary-color);
}

.qa-answers h3 {
  margin-bottom: 1.5rem;
  color: var(--primary-color);
}

.answer-item {
  background: var(--bg-light);
  padding: 1.5rem;
  border-radius: 10px;
  margin-bottom: 1.5rem;
}

.answer-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: 1rem;
}

.answer-question {
  font-weight: bold;
  color: var(--primary-color);
  flex: 1;
}

.answer-date {
  color: var(--text-light);
  font-size: 0.9rem;
}

.answer-content {
  color: var(--text-light);
}

.read-more {
  color: var(--secondary-color);
  text-decoration: none;
  margin-top: 0.5rem;
  display: inline-block;
}

.read-more:hover {
  text-decoration: underline;
}

/* 研究动态区域 */
.research-section {
  padding: 5rem 0;
  background: var(--bg-light);
}

.research-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 2rem;
  margin-bottom: 2rem;
}

.research-card {
  background: #fff;
  border-radius: 10px;
  overflow: hidden;
  box-shadow: var(--shadow);
  transition: var(--transition);
}

.research-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-hover);
}

.research-image {
  width: 100%;
  height: 200px;
  overflow: hidden;
}

.research-image img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: var(--transition);
}

.research-card:hover .research-image img {
  transform: scale(1.1);
}

.research-content {
  padding: 1.5rem;
}

.research-date {
  color: var(--text-light);
  font-size: 0.9rem;
}

.research-content h3 {
  margin: 0.5rem 0 1rem;
  color: var(--primary-color);
  font-size: 1.3rem;
}

.research-content p {
  color: var(--text-light);
  margin-bottom: 1rem;
}

.text-center {
  text-align: center;
}

/* 多媒体资源区域 */
.media-section {
  padding: 5rem 0;
  background: #fff;
}

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

.media-card {
  background: linear-gradient(135deg, var(--secondary-color), #764ba2);
  padding: 2rem;
  border-radius: 10px;
  text-align: center;
  color: #fff;
  text-decoration: none;
  transition: var(--transition);
  box-shadow: var(--shadow);
}

.media-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-hover);
}

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

.media-card h3 {
  margin-bottom: 0.5rem;
  font-size: 1.5rem;
}

.media-card p {
  opacity: 0.9;
}

/* 页脚 */
.footer {
  background: var(--primary-color);
  color: #fff;
  padding: 3rem 0 1rem;
}

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

.footer-section h4 {
  margin-bottom: 1rem;
  color: var(--secondary-color);
}

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

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

.footer-section a {
  color: #fff;
  text-decoration: none;
  transition: var(--transition);
}

.footer-section a:hover {
  color: var(--secondary-color);
}

.social-links {
  display: flex;
  gap: 1rem;
}

.social-links a {
  width: 40px;
  height: 40px;
  background: rgba(255,255,255,0.1);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: var(--transition);
}

.social-links a:hover {
  background: var(--secondary-color);
  transform: translateY(-3px);
}

.footer-bottom {
  text-align: center;
  padding-top: 2rem;
  border-top: 1px solid rgba(255,255,255,0.1);
  color: rgba(255,255,255,0.7);
}

/* 动画 */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes pulse {
  0%, 100% {
    transform: scale(1);
  }
  50% {
    transform: scale(1.1);
  }
}

/* 响应式设计 */
@media (max-width: 768px) {
  .hamburger {
    display: flex;
  }

  .nav-menu {
    position: fixed;
    left: -100%;
    top: 70px;
    flex-direction: column;
    background: var(--primary-color);
    width: 100%;
    text-align: center;
    transition: var(--transition);
    padding: 2rem 0;
  }

  .nav-menu.active {
    left: 0;
  }

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

  .hero-subtitle {
    font-size: 1.2rem;
  }

  .section-header h2 {
    font-size: 2rem;
  }

  .featured-card {
    grid-template-columns: 1fr;
  }

  .qa-container {
    grid-template-columns: 1fr;
  }

  .intro-grid,
  .research-grid,
  .media-grid {
    grid-template-columns: 1fr;
  }

  .timeline-map {
    height: 400px;
  }
}

/* 通用工具类 */
.mt-1 { margin-top: 1rem; }
.mt-2 { margin-top: 2rem; }
.mt-3 { margin-top: 3rem; }
.mb-1 { margin-bottom: 1rem; }
.mb-2 { margin-bottom: 2rem; }
.mb-3 { margin-bottom: 3rem; }