/* 全局样式设置 */
body {
  margin: 0;
  padding: 0;
  background: linear-gradient(135deg, #2c3e50, #4b0082); /* 背景渐变色 */
  font-family: 'Roboto', sans-serif; /* 设置字体 */
  color: #ecf0f1; /* 正文字体颜色 */
  line-height: 1.6;
}

/* 容器样式 */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 20px;
}

/* 顶部导航栏 */
.navbar {
  position: fixed;
  top: 0;
  width: 100%;
  background-color: rgba(44, 62, 80, 0.9); /* 半透明背景色 */
  padding: 10px 20px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  z-index: 1000;
}

.navbar .logo {
  font-size: 24px;
  font-weight: bold;
}

.navbar ul {
  list-style: none;
  display: flex;
  gap: 15px;
}

.navbar ul li a {
  color: #ecf0f1;
  text-decoration: none;
  font-size: 16px;
  transition: color 0.3s;
}

.navbar ul li a:hover {
  color: #1abc9c; /* 鼠标悬停颜色变化 */
}

/* 侧边栏 */
.sidebar {
  position: fixed;
  left: 0;
  top: 60px; /* 导航栏高度 */
  width: 200px;
  background-color: #2c3e50;
  height: 100%;
  padding: 20px;
  box-sizing: border-box;
}

.sidebar ul {
  list-style: none;
  padding: 0;
}

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

.sidebar ul li a {
  color: #bdc3c7;
  text-decoration: none;
  font-size: 16px;
  transition: color 0.3s;
}

.sidebar ul li a:hover {
  color: #1abc9c;
}

/* 主要内容区域 */
.main-content {
  margin-left: 220px; /* 侧边栏宽度 + 一些间隔 */
  padding: 80px 20px 20px 20px; /* 顶部预留导航栏空间 */
  box-sizing: border-box;
}

/* 章节导航 */
.chapter-nav {
  position: fixed;
  right: 20px;
  top: 80px;
  background-color: rgba(44, 62, 80, 0.8);
  padding: 10px;
  border-radius: 8px;
}

.chapter-nav ul {
  list-style: none;
  padding: 0;
  margin: 0;
}

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

.chapter-nav ul li a {
  color: #ecf0f1;
  text-decoration: none;
  font-size: 14px;
  transition: color 0.3s;
}

.chapter-nav ul li a:hover {
  color: #1abc9c;
}

/* 卡片样式 */
.card {
  background-color: #34495e;
  border-radius: 10px;
  box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
  padding: 20px;
  margin-bottom: 20px;
  transition: transform 0.3s, box-shadow 0.3s;
}

.card:hover {
  transform: scale(1.05);
  box-shadow: 0 8px 12px rgba(0, 0, 0, 0.2);
}

/* 图片样式 */
.card img {
  width: 100%;
  border-radius: 10px;
  box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
  transition: transform 0.3s;
}

.card img:hover {
  transform: scale(1.05);
}

/* 标题样式 */
h2, h3, h4 {
  color: #ecf0f1;
}

h2 {
  font-size: 28px;
  margin-bottom: 10px;
}

h3 {
  font-size: 22px;
  margin-bottom: 8px;
}

h4 {
  font-size: 18px;
  margin-bottom: 6px;
}

/* 段落样式 */
p {
  font-size: 16px;
  color: #bdc3c7;
  margin-bottom: 15px;
}

/* 代码块样式 */
pre {
  background-color: #2c3e50;
  padding: 15px;
  border-radius: 8px;
  overflow-x: auto;
  margin-bottom: 15px;
}

pre code {
  color: #1abc9c;
  font-family: 'Courier New', Courier, monospace;
  font-size: 14px;
}

/* 提示信息样式 */
.promotion {
  background-color: #1abc9c;
  color: #2c3e50;
  padding: 15px;
  text-align: center;
  font-size: 18px;
  border-radius: 8px;
  margin-bottom: 20px;
}

/* 响应式设计 */
@media (max-width: 768px) {
  .sidebar {
    display: none;
  }
  
  .main-content {
    margin-left: 0;
    padding: 80px 10px 10px 10px;
  }
  
  .chapter-nav {
    display: none;
  }
  
  .navbar ul {
    flex-direction: column;
    gap: 10px;
  }
}

@media (max-width: 480px) {
  .navbar .logo {
    font-size: 20px;
  }
  
  h2 {
    font-size: 24px;
  }
  
  h3 {
    font-size: 20px;
  }
  
  p {
    font-size: 14px;
  }
}