/* 基本样式 */
  body {
    margin: 0;
    font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
    background: linear-gradient(135deg, #E8F5E9 0%, #FFF9C4 100%);
    color: #2E7D32;
    line-height: 1.6;
    font-size: 16px;
    transition: background 0.5s ease;
  }
  
  h2, h3, h4 {
    color: #FFD54F;
    position: relative;
    transition: color 0.3s ease, font-weight 0.3s ease;
  }
  
  h2::after, h3::after, h4::after {
    content: '';
    display: block;
    width: 50px;
    height: 3px;
    background: #BA68C8;
    margin-top: 8px;
    border-radius: 2px;
  }
  
  /* 导航栏 */
  nav {
    position: fixed;
    top: 0;
    width: 100%;
    background: rgba(46, 125, 50, 0.9);
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
    z-index: 1000;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 10px 20px;
  }
  
  nav .logo {
    color: #FFD54F;
    font-size: 24px;
    font-weight: bold;
    text-decoration: none;
  }
  
  nav ul {
    list-style: none;
    display: flex;
    margin: 0;
    padding: 0;
  }
  
  nav ul li {
    margin-left: 20px;
  }
  
  nav ul li a {
    color: #FFFFFF;
    text-decoration: none;
    font-size: 16px;
    position: relative;
    padding: 5px;
    transition: color 0.3s ease;
  }
  
  nav ul li a::before {
    content: '';
    position: absolute;
    width: 0%;
    height: 2px;
    bottom: 0;
    left: 0;
    background-color: #BA68C8;
    transition: width 0.3s ease;
  }
  
  nav ul li a:hover::before {
    width: 100%;
  }
  
  nav ul li a:hover {
    color: #FFD54F;
  }
  
  /* 主标题区 */
  .header {
    height: 100vh;
    background: url('https://images.gptkong.com/article/b/745_1.png') no-repeat center center/cover;
    display: flex;
    justify-content: center;
    align-items: center;
    position: relative;
    text-align: center;
    color: #FFFFFF;
  }
  
  .header::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(46, 125, 50, 0.5);
  }
  
  .header h1 {
    position: relative;
    font-size: 48px;
    max-width: 80%;
    animation: fadeIn 2s ease-in-out;
  }
  
  /* 章节导航 */
  .toc {
    position: fixed;
    top: 60px;
    right: 20px;
    background: rgba(255, 255, 255, 0.8);
    padding: 15px;
    border-radius: 8px;
    box-shadow: 0 2px 8px rgba(0,0,0,0.1);
    max-height: 80vh;
    overflow-y: auto;
    transition: transform 0.3s ease;
  }
  
  .toc h3 {
    margin-top: 0;
    color: #2E7D32;
  }
  
  .toc ul {
    list-style: none;
    padding: 0;
  }
  
  .toc ul li {
    margin-bottom: 10px;
  }
  
  .toc ul li a {
    color: #2E7D32;
    text-decoration: none;
    transition: color 0.3s ease;
  }
  
  .toc ul li a:hover {
    color: #BA68C8;
  }
  
  /* 内容区 */
  article {
    padding: 80px 20px 40px 20px;
    max-width: 1200px;
    margin: 0 auto;
  }
  
  section {
    margin-bottom: 60px;
    padding: 20px;
    background: rgba(255, 255, 255, 0.9);
    border-left: 5px solid #BA68C8;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
    border-radius: 8px;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
  }
  
  section:hover {
    transform: translateY(-5px);
    box-shadow: 0 6px 12px rgba(0,0,0,0.15);
  }
  
  section img {
    max-width: 100%;
    height: auto;
    display: block;
    margin: 20px auto;
    border-radius: 10px;
    box-shadow: 0 4px 8px rgba(0,0,0,0.2);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
  }
  
  section img:hover {
    transform: scale(1.05);
    box-shadow: 0 6px 12px rgba(0,0,0,0.3);
  }
  
  /* 底部 */
  footer {
    background: rgba(46, 125, 50, 0.9);
    color: #FFFFFF;
    text-align: center;
    padding: 20px;
    position: relative;
  }
  
  footer a {
    color: #FFD54F;
    text-decoration: none;
    margin: 0 10px;
    transition: color 0.3s ease;
  }
  
  footer a:hover {
    color: #BA68C8;
  }
  
  /* 响应式设计 */
  @media (max-width: 768px) {
    nav ul {
      display: none;
    }
    
    .toc {
      display: none;
    }
    
    .header h1 {
      font-size: 32px;
      max-width: 90%;
    }
    
    section {
      padding: 15px;
    }
  }
  
  @media (min-width: 769px) {
    .toc {
      display: block;
    }
  }
  
  /* 动画 */
  @keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
  }
  
  /* 链接样式 */
  a {
    color: #BA68C8;
    text-decoration: none;
    position: relative;
    transition: color 0.3s ease;
  }
  
  a::after {
    content: '';
    position: absolute;
    width: 100%;
    transform: scaleX(0);
    height: 2px;
    bottom: -2px;
    left: 0;
    background-color: #BA68C8;
    transform-origin: bottom right;
    transition: transform 0.25s ease-out;
  }
  
  a:hover::after {
    transform: scaleX(1);
    transform-origin: bottom left;
  }
  
  /* 图片边框 */
  img {
    border: 3px solid #FFD54F;
  }