/* AI学习笔记 - 共享样式表 */
/* 所有章节共用此文件，不再内联重复 */

/* ========== CSS变量 ========== */
:root {
  --ai-primary: #4299e1;
  --ai-primary-dark: #2b6cb0;
  --ai-primary-darker: #1a365d;
  --ai-primary-light: #ebf8ff;
  --ai-success: #38a169;
  --ai-success-light: #f0fff4;
  --ai-warning: #d69e2e;
  --ai-warning-light: #fffbeb;
  --ai-error: #e53e3e;
  --ai-info: #3182ce;
  --ai-info-light: #ebf4ff;
  --ai-purple: #805ad5;
  --ai-purple-light: #faf5ff;
  --ai-gray-50: #f7fafc;
  --ai-gray-100: #edf2f7;
  --ai-gray-200: #e2e8f0;
  --ai-gray-300: #cbd5e0;
  --ai-gray-400: #a0aec0;
  --ai-gray-500: #718096;
  --ai-gray-600: #4a5568;
  --ai-gray-700: #2d3748;
  --ai-gray-800: #1a202c;
  --ai-nav-height: 64px;
  --ai-radius: 12px;
  --ai-radius-sm: 8px;
  --ai-radius-xs: 6px;
  --ai-transition: all 0.2s ease;
}

/* ========== 全局基础 ========== */
* { margin: 0; padding: 0; box-sizing: border-box; }
body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  line-height: 1.8; color: var(--ai-gray-700); background-color: var(--ai-gray-50); font-size: 16px;
}
a { color: var(--ai-primary); text-decoration: none; transition: color 0.3s ease; }
a:hover { color: var(--ai-primary-dark); }

/* ========== 导航栏 ========== */
.ai-nav {
  position: fixed; top: 0; left: 0; right: 0; z-index: 1000;
  background: rgba(255,255,255,0.95); backdrop-filter: blur(10px);
  box-shadow: 0 2px 10px rgba(0,0,0,0.1); padding: 0 2rem;
  height: var(--ai-nav-height); display: flex; align-items: center; justify-content: space-between;
}
.ai-nav-brand { font-size: 1.4rem; font-weight: 700; color: var(--ai-primary-dark); display: flex; align-items: center; gap: 0.5rem; }
.ai-nav-brand i { color: var(--ai-primary); }
.ai-nav-links { display: flex; list-style: none; gap: 1.5rem; align-items: center; }
.ai-nav-links a { color: var(--ai-gray-600); font-weight: 500; font-size: 0.95rem; padding: 0.5rem 0; position: relative; }
.ai-nav-links a::after { content: ''; position: absolute; bottom: 0; left: 0; width: 0; height: 2px; background: var(--ai-primary); transition: width 0.3s ease; }
.ai-nav-links a:hover::after, .ai-nav-links a.active::after { width: 100%; }
.ai-nav-toggle { display: none; background: none; border: none; font-size: 1.5rem; color: var(--ai-gray-600); cursor: pointer; }

/* ========== Hero ========== */
.ai-hero {
  background: linear-gradient(135deg, var(--ai-primary-darker) 0%, var(--ai-primary-dark) 50%, var(--ai-primary) 100%);
  color: #fff; padding: 8rem 2rem 4rem; text-align: center;
  margin-top: var(--ai-nav-height); position: relative; overflow: hidden;
}
.ai-hero::before {
  content: ''; position: absolute; top: 0; left: 0; right: 0; bottom: 0;
  background: url("data:image/svg+xml,%3Csvg width='60' height='60' viewBox='0 0 60 60' xmlns='http://www.w3.org/2000/svg'%3E%3Cg fill='none' fill-rule='evenodd'%3E%3Cg fill='%23ffffff' fill-opacity='0.05'%3E%3Cpath d='M36 34v-4h-2v4h-4v2h4v4h2v-4h4v-2h-4zm0-30V0h-2v4h-4v2h4v4h2V6h4V4h-4zM6 34v-4H4v4H0v2h4v4h2v-4h4v-2H6zM6 4V0H4v4H0v2h4v4h2V6h4V4H6z'/%3E%3C/g%3E%3C/g%3E%3C/svg%3E");
  opacity: 0.3;
}
.ai-hero h1, .hero-title { font-size: 3rem; font-weight: 800; margin-bottom: 1rem; position: relative; letter-spacing: -0.02em; }
.ai-hero p, .hero-subtitle { font-size: 1.25rem; max-width: 700px; margin: 0 auto 2rem; opacity: 0.9; position: relative; line-height: 1.8; }
.hero-description { font-size: 1rem; max-width: 700px; margin: 0 auto 2rem; opacity: 0.9; position: relative; line-height: 1.8; }
.hero-content { position: relative; max-width: 800px; margin: 0 auto; }
.ai-hero-badges { display: flex; justify-content: center; gap: 1rem; flex-wrap: wrap; position: relative; }
.ai-hero-badge { background: rgba(255,255,255,0.15); border: 1px solid rgba(255,255,255,0.3); padding: 0.5rem 1.2rem; border-radius: 50px; font-size: 0.9rem; font-weight: 500; backdrop-filter: blur(5px); }

/* ========== 布局 ========== */
.ai-content-wrapper { display: flex; max-width: 1400px; margin: 0 auto; padding: 2rem; gap: 2rem; }
.ai-main { flex: 1; min-width: 0; max-width: 900px; margin: 0 auto; padding: 2rem; }

.content-wrapper { max-width: 1000px; margin: 0 auto; padding: 2rem; }
.main-content { background: #fff; border-radius: var(--ai-radius); box-shadow: 0 2px 12px rgba(0,0,0,0.06); padding: 2.5rem 3rem; margin-top: 2rem; }

/* ========== 章节标题 ========== */
.ai-section-title {
  font-size: 2rem; font-weight: 700; color: var(--ai-primary-darker);
  margin: 3rem 0 1.5rem; padding-bottom: 0.75rem; border-bottom: 3px solid var(--ai-primary);
  display: flex; align-items: center; gap: 0.75rem;
}
.ai-section-title i { color: var(--ai-primary); font-size: 1.5rem; }
.ai-section-subtitle {
  font-size: 1.4rem; font-weight: 600; color: var(--ai-primary-dark);
  margin: 2rem 0 1rem; padding-left: 0.75rem; border-left: 4px solid var(--ai-primary);
}

/* ========== 学习目标/前置要求/练习/总结 框 ========== */
.ai-box { border-radius: var(--ai-radius); padding: 1.5rem 2rem; margin: 1.5rem 0; position: relative; }
.ai-box::before {
  font-family: 'Font Awesome 6 Free'; font-weight: 900; position: absolute;
  top: -12px; left: 1.5rem; color: #fff; width: 24px; height: 24px;
  border-radius: 50%; display: flex; align-items: center; justify-content: center; font-size: 0.7rem;
}
.ai-box h4 { font-size: 1.1rem; margin-bottom: 0.75rem; display: flex; align-items: center; gap: 0.5rem; }
.ai-box ul, .ai-box ol { list-style: none; padding: 0; }
.ai-box li { padding: 0.3rem 0; padding-left: 1.5rem; position: relative; }

.ai-box--objectives { background: linear-gradient(135deg, #ebf8ff 0%, #e6fffa 100%); border: 2px solid #90cdf4; }
.ai-box--objectives::before { content: '\f02d'; background: var(--ai-primary); }
.ai-box--objectives h4 { color: var(--ai-primary-dark); }
.ai-box--objectives li::before { content: '\f00c'; font-family: 'Font Awesome 6 Free'; font-weight: 900; position: absolute; left: 0; color: var(--ai-success); font-size: 0.8rem; }

.ai-box--prereq { background: linear-gradient(135deg, #fffff0 0%, #fefcbf 100%); border: 2px solid #ecc94b; }
.ai-box--prereq::before { content: '\f0e7'; background: #ecc94b; }
.ai-box--prereq h4 { color: #975a16; }
.ai-box--prereq li::before { content: '\f0da'; font-family: 'Font Awesome 6 Free'; font-weight: 900; position: absolute; left: 0; color: #d69e2e; font-size: 0.8rem; }

.ai-box--exercise { background: linear-gradient(135deg, #faf5ff 0%, #f3e8ff 100%); border: 2px solid #b794f4; margin: 2rem 0; }
.ai-box--exercise::before { content: '\f4d6'; background: var(--ai-purple); }
.ai-box--exercise h4 { color: #6b46c1; margin-bottom: 1rem; }
.ai-exercise-item { background: rgba(255,255,255,0.7); border-radius: var(--ai-radius-sm); padding: 1rem 1.25rem; margin-bottom: 0.75rem; border-left: 3px solid var(--ai-purple); }
.ai-exercise-item .num { font-weight: 700; color: #6b46c1; margin-right: 0.5rem; }

.ai-box--summary { background: linear-gradient(135deg, #f0fff4 0%, #e6fffa 100%); border: 2px solid #68d391; margin: 2rem 0; }
.ai-box--summary::before { content: '\f0eb'; background: var(--ai-success); }
.ai-box--summary h4 { color: #276749; }
.ai-box--summary li::before { content: '\f111'; font-family: 'Font Awesome 6 Free'; font-weight: 900; position: absolute; left: 0; color: var(--ai-success); font-size: 0.4rem; top: 0.85rem; }

.ai-box--tip { background: linear-gradient(135deg, #ebf8ff 0%, #e6fffa 100%); border: 2px solid #90cdf4; margin: 2rem 0; }
.ai-box--tip::before { content: '\f0eb'; background: var(--ai-primary); }
.ai-box--tip h4 { color: var(--ai-primary-dark); }

.ai-box--warning { background: linear-gradient(135deg, #fffff0 0%, #feebc8 100%); border: 2px solid #f6ad55; margin: 2rem 0; }
.ai-box--warning::before { content: '\f071'; background: var(--ai-warning); }
.ai-box--warning h4 { color: #9c4221; }

.ai-box--reading { background: linear-gradient(135deg, #faf5ff 0%, #f3e8ff 100%); border: 2px solid #b794f4; margin: 2rem 0; }
.ai-box--reading::before { content: '\f02e'; background: var(--ai-purple); }
.ai-box--reading h4 { color: #6b46c1; }
.ai-box--reading li::before { content: '\f0da'; font-family: 'Font Awesome 6 Free'; font-weight: 900; position: absolute; left: 0; color: var(--ai-purple); font-size: 0.7rem; top: 0.7rem; }

/* ========== 提示/警告/成功/信息框 ========== */
.ai-tip, .ai-warning, .ai-success, .ai-info {
  border-radius: var(--ai-radius-sm); padding: 1.25rem 1.5rem; margin: 1.25rem 0;
  position: relative; padding-left: 3.5rem;
}
.ai-tip { background: #ebf8ff; border: 1px solid #90cdf4; }
.ai-tip::before { content: '\f0eb'; font-family: 'Font Awesome 6 Free'; font-weight: 900; position: absolute; left: 1.25rem; top: 1.25rem; color: var(--ai-primary); font-size: 1.1rem; }
.ai-warning { background: var(--ai-warning-light); border: 1px solid #f6e05e; }
.ai-warning::before { content: '\f071'; font-family: 'Font Awesome 6 Free'; font-weight: 900; position: absolute; left: 1.25rem; top: 1.25rem; color: var(--ai-warning); font-size: 1.1rem; }
.ai-success { background: var(--ai-success-light); border: 1px solid #9ae6b4; }
.ai-success::before { content: '\f058'; font-family: 'Font Awesome 6 Free'; font-weight: 900; position: absolute; left: 1.25rem; top: 1.25rem; color: var(--ai-success); font-size: 1.1rem; }
.ai-info { background: var(--ai-info-light); border: 1px solid #90cdf4; }
.ai-info::before { content: '\f05a'; font-family: 'Font Awesome 6 Free'; font-weight: 900; position: absolute; left: 1.25rem; top: 1.25rem; color: var(--ai-info); font-size: 1.1rem; }
.ai-tip h5 { margin-bottom: 0.5rem; font-size: 0.95rem; color: var(--ai-primary-dark); }
.ai-warning h5 { margin-bottom: 0.5rem; font-size: 0.95rem; color: #975a16; }
.ai-success h5 { margin-bottom: 0.5rem; font-size: 0.95rem; color: #276749; }
.ai-info h5 { margin-bottom: 0.5rem; font-size: 0.95rem; color: #2a4365; }

/* ========== 代码块 ========== */
.ai-code { position: relative; margin: 1.25rem 0; border-radius: var(--ai-radius-sm); overflow: hidden; box-shadow: 0 2px 8px rgba(0,0,0,0.1); }
.ai-code-header { background: #1d1f21; color: #c5c8c6; padding: 0.5rem 1rem; display: flex; align-items: center; justify-content: space-between; font-size: 0.85rem; }
.ai-code-header .lang { display: flex; align-items: center; gap: 0.5rem; }
.ai-code-header .lang i { color: var(--ai-primary); }
.ai-code-header .copy-btn { background: rgba(255,255,255,0.1); border: 1px solid rgba(255,255,255,0.2); color: #c5c8c6; padding: 0.25rem 0.75rem; border-radius: 4px; cursor: pointer; font-size: 0.8rem; display: flex; align-items: center; gap: 0.3rem; transition: all 0.2s; }
.ai-code-header .copy-btn:hover { background: rgba(255,255,255,0.2); color: #fff; }
.ai-code pre { margin: 0; border-radius: 0; }
.ai-code pre code { font-family: 'Fira Code', 'Consolas', 'Monaco', monospace; font-size: 0.9rem; line-height: 1.6; }

/* ========== 表格 ========== */
.ai-table { width: 100%; border-collapse: collapse; margin: 1.5rem 0; border-radius: var(--ai-radius-sm); overflow: hidden; box-shadow: 0 2px 8px rgba(0,0,0,0.06); }
.ai-table thead { background: var(--ai-primary); color: #fff; }
.ai-table th { padding: 0.85rem 1.25rem; text-align: left; font-weight: 600; font-size: 0.9rem; }
.ai-table td { padding: 0.75rem 1.25rem; border-bottom: 1px solid var(--ai-gray-200); font-size: 0.92rem; }
.ai-table tbody tr:hover { background: var(--ai-gray-50); }
.ai-table tbody tr:last-child td { border-bottom: none; }
@media (max-width: 768px) {
  .ai-table { display: block; overflow-x: auto; }
}

/* ========== 页脚 ========== */
.ai-footer { background: var(--ai-gray-800); color: var(--ai-gray-400); padding: 2rem; text-align: center; margin-top: 3rem; }
.ai-footer .footer-content p { margin: 0.3rem 0; font-size: 0.9rem; }
.ai-footer a { color: var(--ai-primary); }
.ai-footer a:hover { color: var(--ai-primary-light); }

/* ========== 右侧TOC侧边栏 ========== */
.ai-toc {
  width: 280px; flex-shrink: 0; position: sticky; top: 80px;
  height: fit-content; max-height: calc(100vh - 100px);
  overflow-y: auto; background: #fff; border-radius: var(--ai-radius);
  padding: 1.5rem; box-shadow: 0 4px 15px rgba(0,0,0,0.08); border: 1px solid var(--ai-gray-200);
}
.ai-toc::-webkit-scrollbar { width: 4px; }
.ai-toc::-webkit-scrollbar-thumb { background: var(--ai-gray-300); border-radius: 2px; }
.ai-toc h3 { font-size: 1rem; color: var(--ai-primary-darker); margin-bottom: 1rem; padding-bottom: 0.5rem; border-bottom: 2px solid var(--ai-gray-200); display: flex; align-items: center; gap: 0.5rem; }
.ai-toc h3 i { color: var(--ai-primary); }
.ai-toc ul { list-style: none; padding: 0; }
.ai-toc li { margin-bottom: 0.25rem; }
.ai-toc a { display: block; padding: 0.4rem 0.75rem; color: var(--ai-gray-600); font-size: 0.88rem; border-radius: var(--ai-radius-xs); transition: all 0.2s; border-left: 3px solid transparent; }
.ai-toc a:hover { background: var(--ai-primary-light); color: var(--ai-primary-dark); border-left-color: var(--ai-primary); }
.ai-toc a.active { background: var(--ai-primary-light); color: var(--ai-primary-dark); border-left-color: var(--ai-primary); font-weight: 600; }
.ai-toc .sub { padding-left: 1rem; }
.ai-toc .sub a { font-size: 0.82rem; color: var(--ai-gray-500); padding: 0.3rem 0.75rem; }
.ai-toc .divider { height: 1px; background: var(--ai-gray-200); margin: 0.75rem 0; }

/* ========== 章节导航 ========== */
.ai-chapter-nav { display: flex; justify-content: space-between; align-items: center; padding: 1.5rem 2rem; background: #fff; border-top: 1px solid var(--ai-gray-200); max-width: 900px; margin: 0 auto; }
.ai-chapter-nav a { padding: 0.5rem 1rem; border-radius: var(--ai-radius-xs); font-weight: 500; transition: var(--ai-transition); }
.ai-chapter-nav a:hover { background: var(--ai-primary-light); color: var(--ai-primary-dark); }
.ai-chapter-nav .disabled { opacity: 0.4; pointer-events: none; }
.ai-chapter-nav .toc-link { background: var(--ai-gray-100); }

/* ========== 完成按钮 ========== */
.ai-complete-btn {
  display: flex; align-items: center; gap: 0.5rem;
  padding: 0.75rem 1.5rem; margin: 2rem auto;
  background: var(--ai-gray-100); border: 2px solid var(--ai-gray-300);
  border-radius: var(--ai-radius-sm); cursor: pointer;
  font-size: 0.95rem; font-weight: 600; color: var(--ai-gray-600);
  transition: all 0.3s ease; width: fit-content;
}
.ai-complete-btn:hover { border-color: var(--ai-success); color: var(--ai-success); background: var(--ai-success-light); }
.ai-complete-btn.done { background: var(--ai-success); border-color: var(--ai-success); color: #fff; pointer-events: none; }

/* ========== 移动端TOC抽屉 ========== */
.ai-mobile-toc-overlay { display: none; position: fixed; top: 0; left: 0; right: 0; bottom: 0; background: rgba(0,0,0,0.5); z-index: 1099; }
.ai-mobile-toc-overlay.show { display: block; }
.ai-mobile-toc {
  position: fixed; top: 0; right: -320px; width: 320px; height: 100vh;
  background: #fff; z-index: 1100; box-shadow: -4px 0 20px rgba(0,0,0,0.15);
  overflow-y: auto; padding: 1.5rem; transition: right 0.3s ease;
}
.ai-mobile-toc.show { right: 0; }
.ai-mobile-toc-close { position: absolute; top: 1rem; right: 1rem; background: none; border: none; font-size: 1.5rem; color: var(--ai-gray-500); cursor: pointer; }
.ai-mobile-toc h3 { font-size: 1.1rem; color: var(--ai-primary-darker); margin-bottom: 1rem; padding-bottom: 0.5rem; border-bottom: 2px solid var(--ai-gray-200); }
.ai-mobile-toc-toggle { display: none; position: fixed; bottom: 2rem; right: 1rem; z-index: 999; width: 50px; height: 50px; border-radius: 50%; background: var(--ai-primary); color: #fff; border: none; font-size: 1.2rem; cursor: none; box-shadow: 0 4px 15px rgba(66,153,225,0.4); }
.ai-mobile-toc-toggle:hover { background: var(--ai-primary-dark); }

/* ========== 打印样式 ========== */
@media print {
  .ai-nav, .ai-chapter-nav, .ai-complete-btn, .ai-toc, .ai-mobile-toc, .ai-mobile-toc-toggle, .ai-mobile-toc-overlay, .ai-hero { display: none !important; }
  .ai-content-wrapper { padding: 0; max-width: 100%; }
  .ai-main { max-width: 100%; }
  .content-wrapper { padding: 0; max-width: 100%; }
  .main-content { box-shadow: none; padding: 0; margin: 0; }
  .ai-code { box-shadow: none; border: 1px solid var(--ai-gray-300); }
  .ai-box, .ai-tip, .ai-warning, .ai-success, .ai-info { break-inside: avoid; }
}

/* ========== 暗黑模式 ========== */
@media (prefers-color-scheme: dark) {
  :root {
    --ai-gray-50: #1a202c; --ai-gray-100: #2d3748; --ai-gray-200: #4a5568;
    --ai-gray-300: #718096; --ai-gray-400: #a0aec0; --ai-gray-500: #cbd5e0;
    --ai-gray-600: #e2e8f0; --ai-gray-700: #f7fafc; --ai-gray-800: #ffffff;
    --ai-primary-light: rgba(66,153,225,0.1); --ai-success-light: rgba(56,161,105,0.1);
    --ai-warning-light: rgba(214,158,46,0.1); --ai-info-light: rgba(49,130,206,0.1);
    --ai-purple-light: rgba(128,90,213,0.1);
  }
  body { color: #e2e8f0; background-color: #1a202c; }
  .ai-nav { background: rgba(26,32,44,0.95); }
  .ai-toc, .ai-mobile-toc { background: #2d3748; }
  .ai-code-header { background: #0d1117; }
  .ai-box--objectives, .ai-box--prereq, .ai-box--exercise, .ai-box--summary { background: rgba(255,255,255,0.05); }
  .ai-tip, .ai-warning, .ai-success, .ai-info { background: rgba(255,255,255,0.05); }
  .ai-exercise-item { background: rgba(255,255,255,0.05); }
  .ai-chapter-nav { background: #2d3748; border-color: #4a5568; }
  .ai-nav-links { background: #2d3748; }
  .ai-mobile-toc-toggle { background: var(--ai-primary); box-shadow: 0 4px 15px rgba(66,153,225,0.3); }
  .ai-box h4, .ai-tip h4, .ai-warning h4, .ai-success h4, .ai-info h4 { color: #f7fafc; }
  .ai-section-title { color: #f7fafc; border-bottom-color: var(--ai-primary); }
  .ai-section-subtitle { color: #e2e8f0; border-left-color: var(--ai-primary); }
  .main-content { background: #2d3748; }
  .ai-table { box-shadow: 0 2px 8px rgba(0,0,0,0.2); }
  .ai-table th { background: var(--ai-primary-dark); }
  .ai-table td { border-bottom-color: var(--ai-gray-700); }
  .ai-table tbody tr:hover { background: rgba(255,255,255,0.05); }
  .ai-footer { background: #1a202c; color: var(--ai-gray-500); }
  .ai-box--tip, .ai-box--warning, .ai-box--reading { background: rgba(255,255,255,0.05); }
}

/* ========== 响应式 ========== */
@media (max-width: 1024px) {
  .ai-toc { display: none; }
  .ai-content-wrapper { max-width: 100%; }
  .ai-main { max-width: 100%; }
  .content-wrapper { max-width: 100%; padding: 1rem; }
  .main-content { padding: 1.5rem; }
  .ai-mobile-toc-toggle { display: flex; align-items: center; justify-content: center; }
}
@media (max-width: 768px) {
  .ai-nav-links { display: none; position: absolute; top: var(--ai-nav-height); left: 0; right: 0; background: #fff; flex-direction: column; padding: 1rem 2rem; box-shadow: 0 4px 10px rgba(0,0,0,0.1); gap: 0.5rem; }
  .ai-nav-links.active { display: flex; }
  .ai-nav-toggle { display: block; }
  .ai-hero { padding: 6rem 1.5rem 3rem; }
  .ai-hero h1 { font-size: 2rem; }
  .ai-hero p { font-size: 1rem; }
  .ai-section-title { font-size: 1.5rem; }
  .ai-content-wrapper { padding: 1rem; }
  .content-wrapper { padding: 0.5rem; }
  .main-content { padding: 1.25rem 1.5rem; margin-top: 1rem; }
  .ai-box, .ai-tip, .ai-warning, .ai-success, .ai-info { padding: 1.25rem 1.5rem; }
}
@media (max-width: 480px) {
  .ai-hero h1 { font-size: 1.6rem; }
  .ai-hero-badges { gap: 0.5rem; }
  .ai-hero-badge { font-size: 0.8rem; padding: 0.4rem 0.8rem; }
  .ai-code pre code { font-size: 0.8rem; }
}

/* ========== 首页专用样式 ========== */
.modules-section, .chapters-section, .learning-paths-section { max-width: 1200px; margin: 0 auto; padding: 3rem 2rem; }
.section-header { text-align: center; margin-bottom: 2rem; }
.section-header h2 { font-size: 1.8rem; font-weight: 700; color: var(--ai-primary-darker); display: flex; align-items: center; justify-content: center; gap: 0.5rem; }
.section-header p { font-size: 1rem; color: var(--ai-gray-600); margin-top: 0.5rem; }
.modules-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 1.5rem; max-width: 1000px; margin: 0 auto; }
.module-card { background: #fff; border-radius: var(--ai-radius); padding: 1.5rem; text-align: center; box-shadow: 0 2px 8px rgba(0,0,0,0.08); border: 1px solid var(--ai-gray-200); transition: transform 0.2s ease, box-shadow 0.2s ease; }
.module-card:hover { transform: translateY(-4px); box-shadow: 0 4px 12px rgba(0,0,0,0.12); }
.module-icon { width: 48px; height: 48px; margin: 0 auto 1rem; display: flex; align-items: center; justify-content: center; font-size: 1.5rem; background: var(--ai-gray-50); border-radius: 50%; }
.module-card h3 { font-size: 1.1rem; font-weight: 600; color: var(--ai-gray-800); margin-bottom: 0.5rem; }
.module-card p { font-size: 0.9rem; color: var(--ai-gray-600); line-height: 1.6; }
.chapters-count { font-size: 0.85rem; color: var(--ai-primary); font-weight: 500; margin-top: 0.75rem; }
.chapter-group { margin-bottom: 2rem; }
.group-title { font-size: 1.3rem; font-weight: 600; color: var(--ai-primary-dark); padding: 0.75rem 1rem; background: var(--ai-gray-100); border-radius: var(--ai-radius-sm); margin-bottom: 1rem; display: flex; align-items: center; gap: 0.5rem; }
.chapter-list { display: grid; gap: 0.75rem; }
.chapter-item { display: flex; align-items: center; background: #fff; padding: 0.75rem 1rem; border-radius: var(--ai-radius-xs); border: 1px solid var(--ai-gray-200); }
.chapter-number { width: 32px; height: 32px; background: var(--ai-primary); color: #fff; border-radius: 50%; display: flex; align-items: center; justify-content: center; font-weight: 700; font-size: 0.85rem; margin-right: 1rem; }
.chapter-item a { font-weight: 500; color: var(--ai-gray-700); flex: 1; }
.chapter-item a:hover { color: var(--ai-primary); }
.chapter-desc { font-size: 0.8rem; color: var(--ai-gray-500); text-align: right; }
.hero-stats { display: flex; justify-content: center; gap: 2rem; margin-top: 1.5rem; }
.hero-stat { text-align: center; }
.hero-stat-number { font-size: 2rem; font-weight: 700; color: #fff; }
.hero-stat-label { font-size: 0.9rem; color: rgba(255,255,255,0.8); }
@media (max-width: 768px) {
  .modules-section, .chapters-section { padding: 2rem 1rem; }
  .modules-grid { grid-template-columns: 1fr; }
  .hero-stats { flex-wrap: wrap; gap: 1rem; }
}

/* ========== 学习建议样式 ========== */
.tips-section { max-width: 1200px; margin: 0 auto; padding: 3rem 2rem; }
.tips-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(250px, 1fr)); gap: 1.5rem; max-width: 1000px; margin: 0 auto; }
.tip-card { background: #fff; border-radius: var(--ai-radius); padding: 1.5rem; text-align: center; box-shadow: 0 2px 8px rgba(0,0,0,0.08); border: 1px solid var(--ai-gray-200); }
.tip-card i { font-size: 2rem; color: var(--ai-primary); margin-bottom: 1rem; }
.tip-card h4 { font-size: 1.1rem; font-weight: 600; color: var(--ai-gray-800); margin-bottom: 0.75rem; }
.tip-card p { font-size: 0.9rem; color: var(--ai-gray-600); line-height: 1.6; }
@media (max-width: 768px) {
  .tips-section { padding: 2rem 1rem; }
  .tips-grid { grid-template-columns: 1fr; }
}

/* ========== 概念图片说明样式 ========== */
.ai-figure {
  margin: 1.5rem 0;
  text-align: center;
}
.ai-figure img {
  max-width: 100%;
  height: auto;
  border-radius: var(--ai-radius);
  box-shadow: 0 2px 12px rgba(0,0,0,0.1);
  border: 1px solid var(--ai-gray-200);
}
.ai-figure figcaption {
  margin-top: 0.5rem;
  font-size: 0.85rem;
  color: var(--ai-gray-500);
  line-height: 1.5;
}
.ai-figure figcaption strong {
  color: var(--ai-gray-700);
}

/* ========== 右侧目录导航 ========== */
.toc-sidebar {
  position: fixed; top: 80px; right: 20px;
  width: 280px; max-height: calc(100vh - 100px);
  background: #fff; border-radius: var(--ai-radius);
  box-shadow: 0 2px 12px rgba(0,0,0,0.1);
  padding: 1.5rem; overflow-y: auto; z-index: 100;
  border: 1px solid var(--ai-gray-200);
}
.toc-sidebar h3 { font-size: 1rem; font-weight: 600; color: var(--ai-gray-800); margin-bottom: 1rem; display: flex; align-items: center; gap: 0.5rem; }
.toc-sidebar ul { list-style: none; padding: 0; margin: 0; }
.toc-sidebar li { margin-bottom: 0.5rem; }
.toc-sidebar li a { display: block; padding: 0.5rem 0.75rem; color: var(--ai-gray-600); font-size: 0.85rem; border-radius: var(--ai-radius-xs); transition: all 0.2s; text-decoration: none; }
.toc-sidebar li a:hover { background: var(--ai-primary-light); color: var(--ai-primary); }
.toc-sidebar li a.active { background: var(--ai-primary); color: #fff; font-weight: 500; }
.toc-sidebar .toc-sub { padding-left: 1rem; margin-top: 0.25rem; }
.toc-sidebar .toc-sub li a { font-size: 0.8rem; color: var(--ai-gray-500); }
.toc-sidebar .toc-divider { height: 1px; background: var(--ai-gray-200); margin: 0.75rem 0; }
@media (max-width: 1200px) { .toc-sidebar { display: none; } }

/* ========== 主内容区布局(配合右侧目录) ========== */
.ai-content-wrapper { display: flex; max-width: 1200px; margin: 0 auto; padding: 2rem; gap: 2rem; }
.ai-content-wrapper .ai-main { flex: 1; max-width: 800px; }
@media (max-width: 1200px) { .ai-content-wrapper { display: block; } .ai-content-wrapper .ai-main { max-width: 900px; } }

/* ========== 进度条样式 ========== */
.progress-section { max-width: 1200px; margin: 0 auto; padding: 1.5rem 2rem; }
.progress-container { max-width: 800px; margin: 0 auto; background: #fff; border-radius: var(--ai-radius); padding: 1.5rem; box-shadow: 0 2px 8px rgba(0,0,0,0.08); border: 1px solid var(--ai-gray-200); }
.progress-header { display: flex; justify-content: space-between; align-items: center; margin-bottom: 1rem; }
.progress-title { font-size: 1rem; font-weight: 600; color: var(--ai-gray-700); display: flex; align-items: center; gap: 0.5rem; }
.progress-percentage { font-size: 1.2rem; font-weight: 700; color: var(--ai-primary); }
.progress-reset { font-size: 0.85rem; color: var(--ai-gray-500); cursor: pointer; display: flex; align-items: center; gap: 0.25rem; }
.progress-reset:hover { color: var(--ai-primary); }
.progress-bar-bg { height: 12px; background: var(--ai-gray-200); border-radius: 6px; overflow: hidden; }
.progress-bar-fill { height: 100%; background: linear-gradient(90deg, var(--ai-primary), var(--ai-success)); border-radius: 6px; width: 0%; transition: width 0.5s ease; }

/* ========== 学习路径推荐样式 ========== */
.paths-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 1.5rem; max-width: 1000px; margin: 0 auto; }
.path-card { background: #fff; border-radius: var(--ai-radius); padding: 1.5rem; box-shadow: 0 2px 8px rgba(0,0,0,0.08); border: 1px solid var(--ai-gray-200); transition: transform 0.2s ease, box-shadow 0.2s ease; position: relative; }
.path-card:hover { transform: translateY(-4px); box-shadow: 0 4px 12px rgba(0,0,0,0.12); }
.path-icon { width: 50px; height: 50px; margin-bottom: 1rem; display: flex; align-items: center; justify-content: center; font-size: 1.5rem; background: var(--ai-gray-50); border-radius: 50%; }
.path-card h3 { font-size: 1.1rem; font-weight: 600; color: var(--ai-gray-800); margin-bottom: 0.75rem; }
.path-route { font-size: 0.9rem; color: var(--ai-primary); margin-bottom: 1rem; font-weight: 500; }
.path-meta { display: flex; flex-wrap: wrap; gap: 0.75rem; margin-bottom: 1rem; }
.path-time { font-size: 0.85rem; color: var(--ai-gray-500); display: flex; align-items: center; gap: 0.25rem; }
.path-audience { font-size: 0.85rem; color: var(--ai-gray-500); background: var(--ai-gray-100); padding: 0.25rem 0.5rem; border-radius: var(--ai-radius-xs); }
.path-btn { display: inline-block; padding: 0.5rem 1.5rem; background: var(--ai-primary); color: #fff; border-radius: var(--ai-radius-xs); font-size: 0.9rem; font-weight: 500; text-decoration: none; transition: background 0.2s ease; }
.path-btn:hover { background: var(--ai-primary-dark); }
@media (max-width: 768px) { .paths-grid { grid-template-columns: 1fr; } }

/* ========== 章节目录样式 ========== */
.toc-section { max-width: 1200px; margin: 0 auto; padding: 3rem 2rem; }
.toc-module { margin-bottom: 2rem; background: #fff; border-radius: var(--ai-radius); overflow: hidden; box-shadow: 0 2px 8px rgba(0,0,0,0.08); border: 1px solid var(--ai-gray-200); }
.toc-module-header { background: var(--ai-gray-100); padding: 1rem 1.5rem; display: flex; align-items: center; gap: 0.75rem; }
.toc-module-header i { font-size: 1.25rem; }
.toc-module-header h3 { font-size: 1.1rem; font-weight: 600; color: var(--ai-gray-800); margin: 0; }
.toc-module-header span { font-size: 0.85rem; color: var(--ai-gray-500); margin-left: auto; }
.toc-list { list-style: none; padding: 0; margin: 0; }
.toc-item { display: flex; align-items: center; padding: 1rem 1.5rem; border-bottom: 1px solid var(--ai-gray-200); gap: 1rem; transition: background 0.2s ease; }
.toc-item:last-child { border-bottom: none; }
.toc-item:hover { background: var(--ai-gray-50); }
.toc-check { width: 24px; height: 24px; display: flex; align-items: center; justify-content: center; color: var(--ai-gray-400); }
.toc-check .fa-check-circle { color: var(--ai-success); }
.toc-number { font-size: 0.85rem; font-weight: 600; color: var(--ai-primary); width: 80px; }
.toc-info { flex: 1; min-width: 0; }
.toc-title { font-size: 1rem; font-weight: 500; color: var(--ai-gray-700); margin-bottom: 0.25rem; }
.toc-desc { font-size: 0.85rem; color: var(--ai-gray-500); line-height: 1.5; }
.toc-btn { padding: 0.5rem 1rem; background: var(--ai-primary); color: #fff; border-radius: var(--ai-radius-xs); font-size: 0.85rem; font-weight: 500; text-decoration: none; white-space: nowrap; transition: background 0.2s ease; }
.toc-btn:hover { background: var(--ai-primary-dark); }
@media (max-width: 768px) {
  .toc-section { padding: 2rem 1rem; }
  .toc-item { flex-wrap: wrap; padding: 1rem; }
  .toc-number { width: auto; order: 2; }
  .toc-info { order: 3; width: 100%; }
  .toc-btn { order: 1; margin-bottom: 0.5rem; }
  .toc-check { order: 4; }
}

/* ========== 附录样式 ========== */
.appendix-section { max-width: 1200px; margin: 0 auto; padding: 3rem 2rem; }
.appendix-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 1rem; max-width: 1000px; margin: 0 auto; }
.appendix-card { background: #fff; border-radius: var(--ai-radius-sm); padding: 1.25rem; text-align: center; box-shadow: 0 2px 8px rgba(0,0,0,0.08); border: 1px solid var(--ai-gray-200); transition: transform 0.2s ease; }
.appendix-card:hover { transform: translateY(-2px); }
.appendix-card i { font-size: 1.5rem; color: var(--ai-primary); margin-bottom: 0.75rem; }
.appendix-card h4 { font-size: 1rem; font-weight: 600; color: var(--ai-gray-800); margin-bottom: 0.5rem; }
.appendix-card p { font-size: 0.85rem; color: var(--ai-gray-600); }
@media (max-width: 768px) { .appendix-grid { grid-template-columns: 1fr; } }

/* ========== 暗黑模式补充 ========== */
@media (prefers-color-scheme: dark) {
  .progress-container, .path-card, .toc-module, .toc-item, .appendix-card { background: #2d3748; border-color: #4a5568; }
  .progress-bar-bg { background: #4a5568; }
  .progress-title, .path-card h3, .toc-title, .appendix-card h4 { color: #f7fafc; }
  .progress-reset, .path-route, .toc-desc, .appendix-card p { color: #cbd5e0; }
  .toc-module-header { background: #4a5568; }
  .toc-module-header h3 { color: #f7fafc; }
  .toc-item:hover { background: rgba(255,255,255,0.05); }
}