/* 全局样式重置和基础设置 */
  * {
    margin: 0;
    padding: 0;
    box-sizing: border-box; /* 设置盒模型为边框盒模型，便于元素的尺寸管理 */
  }

  body {
    font-family: 'Roboto', sans-serif; /* 使用Roboto字体，提高可读性和现代感 */
    background: linear-gradient(135deg, #123456 70%, #E0E0E0 25%, #3F5EFB 5%); /* 设置页面背景为渐变色，主色占70%，辅色占25%，点缀色占5% */
    color: #E0E0E0; /* 全局文字颜色为灰色，保持整体协调 */
    line-height: 1.6; /* 行高设为1.6，提升阅读体验 */
    overflow-x: hidden; /* 防止出现水平滚动条 */
  }

  /* 导航栏样式 */
  .navbar {
    position: fixed; /* 固定在顶部，始终可见 */
    top: 0;
    width: 100%;
    background-color: rgba(18, 52, 86, 0.9); /* 半透明深蓝色背景，体现专业与信任感 */
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 20px 40px;
    z-index: 1000; /* 确保导航栏在最上层 */
    box-shadow: 0 2px 5px rgba(0,0,0,0.5); /* 添加阴影增加层次感 */
  }

  .navbar .logo a {
    color: #FFFFFF; /* LOGO文字为白色 */
    font-size: 1.5em;
    text-decoration: none;
    font-weight: bold;
  }

  .navbar nav a {
    color: #E0E0E0; /* 导航链接为灰色 */
    text-decoration: none;
    margin: 0 15px;
    font-size: 16px;
    transition: color 0.3s ease;
  }

  .navbar nav a:hover {
    color: #C79FEF; /* 悬停时颜色变为淡紫色 */
  }

  /* 侧边导航栏样式 */
  .sidebar {
    position: fixed;
    top: 100px; /* 距离顶部100px，避免与导航栏重叠 */
    right: 20px;
    width: 200px;
  }

  .sidebar ul {
    list-style: none;
  }

  .sidebar ul li {
    margin-bottom: 15px;
  }

  .sidebar ul li a {
    color: #3F5EFB; /* 侧边导航链接为电光蓝 */
    text-decoration: none;
    font-size: 16px;
    transition: color 0.3s ease;
  }

  .sidebar ul li a:hover {
    color: #C79FEF; /* 悬停时变为淡紫色 */
  }

  /* 容器样式 */
  .container {
    max-width: 1200px; /* 最大宽度为1200px */
    margin: 100px auto 50px auto; /* 上方留出导航栏空间 */
    padding: 20px;
    display: grid;
    grid-template-columns: 1fr 200px; /* 主内容和侧边栏布局 */
    grid-gap: 40px;
  }

  /* 主内容区 */
  .main-content {
    grid-column: 1 / 2;
  }

  /* 主要标题样式 */
  h1, h2, h3, h4 {
    font-family: 'Helvetica Neue', sans-serif; /* 使用Helvetica Neue字体，提升视觉冲击力 */
    color: #FFFFFF; /* 标题文字为白色 */
    text-shadow: 2px 2px 4px rgba(0,0,0,0.5); /* 添加文字阴影，增强可读性 */
    margin-bottom: 20px;
  }

  h1 {
    font-size: 2.5em;
    text-align: center;
    margin-top: 50px;
    animation: fadeIn 1s ease-in-out; /* 添加淡入动画 */
  }

  h2 {
    font-size: 2em;
    margin-top: 40px;
  }

  h3 {
    font-size: 1.75em;
    margin-top: 30px;
  }

  h4 {
    font-size: 1.5em;
    margin-top: 25px;
  }

  /* 段落样式 */
  p {
    font-size: 16px;
    color: #E0E0E0;
    margin-bottom: 15px;
  }

  /* 强调文字 */
  p span {
    color: #3F5EFB;
    font-weight: bold;
  }

  /* 图片装饰样式 */
  img.decorative {
    width: 100%;
    max-width: 320px;
    border-radius: 10px; /* 圆角效果 */
    box-shadow: 0 4px 8px rgba(0,0,0,0.3); /* 添加阴影 */
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    margin: 10px;
  }

  img.decorative:hover {
    transform: scale(1.05); /* 悬停时放大 */
    box-shadow: 0 8px 16px rgba(0,0,0,0.5); /* 增强阴影效果 */
  }

  /* 代码块样式 */
  pre {
    background: rgba(18, 52, 86, 0.8);
    padding: 20px;
    border-radius: 8px;
    overflow-x: auto;
    margin-bottom: 20px;
    position: relative;
  }

  code {
    color: #C79FEF;
    font-family: 'Courier New', Courier, monospace;
    font-size: 14px;
    display: block;
  }

  /* 按钮样式 */
  .button {
    background: linear-gradient(45deg, #3F5EFB, #C79FEF);
    color: #fff;
    border: none;
    padding: 10px 20px;
    border-radius: 5px;
    cursor: pointer;
    transition: background 0.3s ease;
    font-size: 16px;
    margin: 10px 0;
  }

  .button:hover {
    background: linear-gradient(45deg, #C79FEF, #3F5EFB);
  }

  /* 折叠区域样式 */
  .collapsible {
    background-color: rgba(63, 94, 251, 0.1);
    color: #E0E0E0;
    cursor: pointer;
    padding: 10px;
    width: 100%;
    border: none;
    text-align: left;
    outline: none;
    font-size: 16px;
    border-radius: 5px;
    transition: background 0.3s ease;
    margin-bottom: 10px;
  }

  .collapsible:hover {
    background-color: rgba(63, 94, 251, 0.2);
  }

  .content {
    padding: 0 15px;
    display: none;
    overflow: hidden;
    background-color: rgba(18, 52, 86, 0.9);
    border-radius: 5px;
    margin-bottom: 20px;
  }

  /* 响应式设计 */
  @media (max-width: 1200px) {
    .container {
      grid-template-columns: 1fr; /* 单列布局 */
    }

    .sidebar {
      display: none; /* 隐藏侧边导航 */
    }
  }

  @media (max-width: 768px) {
    .navbar {
      flex-direction: column;
      padding: 15px 20px;
    }

    .navbar nav {
      margin-top: 10px;
    }

    .navbar nav a {
      margin: 10px 0;
      font-size: 18px;
    }

    h1 {
      font-size: 2em;
    }

    h2 {
      font-size: 1.75em;
    }

    h3 {
      font-size: 1.5em;
    }

    h4 {
      font-size: 1.25em;
    }

    p {
      font-size: 15px;
    }

    img.decorative {
      max-width: 100%;
    }
  }

  /* 动画效果 */
  @keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
  }

  /* 折叠区域展开时的动画 */
  .active + .content {
    display: block;
    animation: fadeIn 0.5s ease-in-out;
  }

  /* 高亮显示可见内容 */
  .visible {
    opacity: 1;
    transform: translateY(0);
    transition: opacity 1s ease-out, transform 1s ease-out;
  }

  /* 章节导航系统样式 */
  .chapter-nav {
    margin-bottom: 20px;
  }

  .chapter-nav ul {
    list-style: none;
    display: flex;
    flex-wrap: wrap;
  }

  .chapter-nav ul li {
    margin-right: 15px;
    margin-bottom: 10px;
  }

  .chapter-nav ul li a {
    color: #3F5EFB;
    text-decoration: none;
    font-size: 16px;
    padding: 5px 10px;
    border: 1px solid #3F5EFB;
    border-radius: 5px;
    transition: background 0.3s ease, color 0.3s ease;
  }

  .chapter-nav ul li a:hover {
    background: #3F5EFB;
    color: #FFFFFF;
  }

  /* 交互动效 */
  .fade-in {
    opacity: 0;
    transform: translateY(20px);
    transition: opacity 1s ease-out, transform 1s ease-out;
  }

  .fade-in.visible {
    opacity: 1;
    transform: translateY(0);
  }

  /* 悬停效果 */
  .interactive-button {
    transition: transform 0.2s ease, box-shadow 0.2s ease;
  }

  .interactive-button:active {
    transform: scale(0.95);
    box-shadow: 0 5px 15px rgba(0,0,0,0.3);
  }

  /* AR模型动画 */
  .ar-model {
    width: 100%;
    height: 500px;
    perspective: 1000px;
  }

  .model-3d {
    width: 100%;
    height: 100%;
    transform-style: preserve-3d;
    animation: rotateModel 10s infinite linear;
  }

  @keyframes rotateModel {
    from {
      transform: rotateY(0deg);
    }
    to {
      transform: rotateY(360deg);
    }
  }