/* ===== 科技风格全局样式 ===== */
@import url('https://fonts.googleapis.com/css2?family=Orbitron:wght@400;700;900&family=JetBrains+Mono:wght@300;400;600&family=Inter:wght@300;400;500;600&display=swap');

:root {
  --bg-primary: #050a0f;
  --bg-secondary: #0a1520;
  --bg-card: #0d1b2a;
  --bg-code: #060d15;
  --accent-cyan: #00d4ff;
  --accent-blue: #0080ff;
  --accent-green: #00ff88;
  --accent-purple: #a855f7;
  --accent-orange: #ff6b35;
  --accent-yellow: #ffd700;
  --text-primary: #e2f0ff;
  --text-secondary: #8baec8;
  --text-muted: #4a6785;
  --border-color: #1a3a5c;
  --border-glow: #00d4ff33;
  --glow-cyan: 0 0 20px #00d4ff44;
  --glow-blue: 0 0 20px #0080ff44;
  --glow-green: 0 0 20px #00ff8844;
  --font-display: 'Orbitron', sans-serif;
  --font-mono: 'JetBrains Mono', monospace;
  --font-body: 'Inter', sans-serif;
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  background-color: var(--bg-primary);
  color: var(--text-primary);
  font-family: var(--font-body);
  line-height: 1.7;
  overflow-x: hidden;
}

/* ===== 背景网格效果 ===== */
body::before {
  content: '';
  position: fixed;
  top: 0; left: 0;
  width: 100%; height: 100%;
  background-image:
    linear-gradient(rgba(0, 212, 255, 0.03) 1px, transparent 1px),
    linear-gradient(90deg, rgba(0, 212, 255, 0.03) 1px, transparent 1px);
  background-size: 50px 50px;
  pointer-events: none;
  z-index: 0;
}

/* ===== 导航栏 ===== */
.navbar {
  position: fixed;
  top: 0;
  width: 100%;
  background: rgba(5, 10, 15, 0.95);
  backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border-color);
  z-index: 1000;
  padding: 0 2rem;
}

.navbar-inner {
  max-width: 1400px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}

.nav-logo {
  font-family: var(--font-display);
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--accent-cyan);
  text-decoration: none;
  letter-spacing: 2px;
  text-shadow: var(--glow-cyan);
}

.nav-logo span {
  color: var(--accent-blue);
}

.nav-links {
  display: flex;
  gap: 0.5rem;
  list-style: none;
}

.nav-links a {
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.85rem;
  padding: 0.4rem 0.8rem;
  border-radius: 4px;
  transition: all 0.2s;
  letter-spacing: 0.5px;
}

.nav-links a:hover {
  color: var(--accent-cyan);
  background: rgba(0, 212, 255, 0.1);
}

/* ===== 主容器 ===== */
.main-container {
  max-width: 1100px;
  margin: 0 auto;
  padding: 100px 2rem 4rem;
  position: relative;
  z-index: 1;
}

/* ===== 页面标题 ===== */
.page-hero {
  text-align: center;
  padding: 4rem 0 3rem;
}

.page-hero .badge {
  display: inline-block;
  background: linear-gradient(135deg, rgba(0, 212, 255, 0.15), rgba(0, 128, 255, 0.15));
  border: 1px solid var(--accent-cyan);
  color: var(--accent-cyan);
  font-family: var(--font-mono);
  font-size: 0.75rem;
  padding: 0.3rem 1rem;
  border-radius: 20px;
  letter-spacing: 2px;
  text-transform: uppercase;
  margin-bottom: 1.5rem;
}

.page-hero h1 {
  font-family: var(--font-display);
  font-size: clamp(2rem, 5vw, 3.5rem);
  font-weight: 900;
  background: linear-gradient(135deg, var(--accent-cyan), var(--accent-blue), var(--accent-purple));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  line-height: 1.2;
  margin-bottom: 1rem;
}

.page-hero p {
  font-size: 1.1rem;
  color: var(--text-secondary);
  max-width: 600px;
  margin: 0 auto;
}

/* ===== 章节标题 ===== */
.chapter-header {
  padding: 3rem 0 2rem;
  border-bottom: 1px solid var(--border-color);
  margin-bottom: 3rem;
}

.chapter-header .chapter-num {
  font-family: var(--font-mono);
  color: var(--accent-cyan);
  font-size: 0.9rem;
  letter-spacing: 3px;
  text-transform: uppercase;
  margin-bottom: 0.5rem;
}

.chapter-header h1 {
  font-family: var(--font-display);
  font-size: clamp(1.8rem, 4vw, 2.8rem);
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 0.8rem;
}

.chapter-header h1 span {
  color: var(--accent-cyan);
}

.chapter-header .desc {
  color: var(--text-secondary);
  font-size: 1rem;
  max-width: 700px;
}

/* ===== 内容区块 ===== */
.section {
  margin-bottom: 3.5rem;
}

.section h2 {
  font-family: var(--font-display);
  font-size: 1.4rem;
  color: var(--accent-cyan);
  margin-bottom: 1.2rem;
  display: flex;
  align-items: center;
  gap: 0.8rem;
}

.section h2::before {
  content: '';
  display: inline-block;
  width: 4px;
  height: 1.2em;
  background: linear-gradient(to bottom, var(--accent-cyan), var(--accent-blue));
  border-radius: 2px;
}

.section h3 {
  font-size: 1.1rem;
  color: var(--accent-blue);
  margin: 1.5rem 0 0.8rem;
  font-weight: 600;
}

.section p {
  color: var(--text-secondary);
  margin-bottom: 1rem;
  line-height: 1.8;
}

/* ===== 概念卡片 ===== */
.concept-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-left: 3px solid var(--accent-cyan);
  border-radius: 8px;
  padding: 1.5rem;
  margin-bottom: 1.5rem;
  position: relative;
  transition: all 0.3s;
}

.concept-card:hover {
  border-color: var(--accent-cyan);
  box-shadow: var(--glow-cyan);
  transform: translateX(4px);
}

.concept-card .concept-title {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--accent-cyan);
  text-transform: uppercase;
  letter-spacing: 2px;
  margin-bottom: 0.5rem;
}

.concept-card h4 {
  font-size: 1.1rem;
  color: var(--text-primary);
  margin-bottom: 0.8rem;
}

.concept-card p {
  color: var(--text-secondary);
  font-size: 0.95rem;
  margin: 0;
}

/* ===== 代码块 ===== */
.code-block {
  background: var(--bg-code);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  overflow: hidden;
  margin: 1.5rem 0;
  position: relative;
}

.code-block-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.6rem 1rem;
  background: rgba(0, 212, 255, 0.05);
  border-bottom: 1px solid var(--border-color);
}

.code-block-header .lang {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--accent-cyan);
  letter-spacing: 1px;
}

.code-block-header .dots {
  display: flex;
  gap: 6px;
}

.code-block-header .dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
}

.dot.red { background: #ff5f57; }
.dot.yellow { background: #febc2e; }
.dot.green { background: #28c840; }

pre {
  padding: 1.5rem;
  overflow-x: auto;
  font-family: var(--font-mono);
  font-size: 0.88rem;
  line-height: 1.7;
}

code {
  font-family: var(--font-mono);
}

/* Syntax highlighting */
.kw { color: #c792ea; }      /* keywords */
.fn { color: #82aaff; }      /* functions */
.str { color: #c3e88d; }     /* strings */
.num { color: #f78c6c; }     /* numbers */
.cm { color: #546e7a; font-style: italic; }  /* comments */
.cls { color: #ffcb6b; }     /* class names */
.bi { color: #89ddff; }      /* builtins */
.op { color: #89ddff; }      /* operators */
.var { color: #eeffff; }     /* variables */
.dec { color: #ff5370; }     /* decorators */

/* Inline code */
code:not(pre code) {
  background: rgba(0, 212, 255, 0.1);
  color: var(--accent-cyan);
  padding: 0.15rem 0.4rem;
  border-radius: 3px;
  font-size: 0.88em;
}

/* ===== 提示框 ===== */
.tip-box {
  display: flex;
  gap: 1rem;
  padding: 1.2rem 1.5rem;
  border-radius: 8px;
  margin: 1.5rem 0;
  border: 1px solid;
}

.tip-box.info {
  background: rgba(0, 128, 255, 0.08);
  border-color: rgba(0, 128, 255, 0.3);
}

.tip-box.success {
  background: rgba(0, 255, 136, 0.08);
  border-color: rgba(0, 255, 136, 0.3);
}

.tip-box.warning {
  background: rgba(255, 107, 53, 0.08);
  border-color: rgba(255, 107, 53, 0.3);
}

.tip-box.ai {
  background: rgba(168, 85, 247, 0.08);
  border-color: rgba(168, 85, 247, 0.3);
}

.tip-icon {
  font-size: 1.3rem;
  flex-shrink: 0;
  margin-top: 0.1rem;
}

.tip-content .tip-title {
  font-weight: 600;
  font-size: 0.9rem;
  margin-bottom: 0.3rem;
}

.tip-box.info .tip-title { color: var(--accent-blue); }
.tip-box.success .tip-title { color: var(--accent-green); }
.tip-box.warning .tip-title { color: var(--accent-orange); }
.tip-box.ai .tip-title { color: var(--accent-purple); }

.tip-content p {
  font-size: 0.9rem;
  color: var(--text-secondary);
  margin: 0;
}

/* ===== 对比表格 ===== */
.compare-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
  margin: 1.5rem 0;
}

.compare-item {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 1.2rem;
}

.compare-item h5 {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  letter-spacing: 1px;
  text-transform: uppercase;
  margin-bottom: 0.8rem;
  padding-bottom: 0.5rem;
  border-bottom: 1px solid var(--border-color);
}

.compare-item.good h5 { color: var(--accent-green); }
.compare-item.bad h5 { color: var(--accent-orange); }

/* ===== 步骤流程 ===== */
.steps {
  counter-reset: step;
  list-style: none;
  padding: 0;
}

.steps li {
  counter-increment: step;
  display: flex;
  gap: 1rem;
  margin-bottom: 1.2rem;
  align-items: flex-start;
}

.steps li::before {
  content: counter(step);
  display: flex;
  align-items: center;
  justify-content: center;
  width: 28px;
  height: 28px;
  background: linear-gradient(135deg, var(--accent-cyan), var(--accent-blue));
  color: var(--bg-primary);
  font-weight: 700;
  font-size: 0.8rem;
  border-radius: 50%;
  flex-shrink: 0;
  margin-top: 2px;
  font-family: var(--font-mono);
}

.steps li p {
  color: var(--text-secondary);
  margin: 0;
}

.steps li strong {
  color: var(--text-primary);
  display: block;
  margin-bottom: 0.2rem;
}

/* ===== 知识点标签 ===== */
.tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin: 1rem 0;
}

.tag {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  padding: 0.25rem 0.7rem;
  border-radius: 3px;
  letter-spacing: 0.5px;
}

.tag.cyan { background: rgba(0, 212, 255, 0.1); color: var(--accent-cyan); border: 1px solid rgba(0, 212, 255, 0.2); }
.tag.blue { background: rgba(0, 128, 255, 0.1); color: var(--accent-blue); border: 1px solid rgba(0, 128, 255, 0.2); }
.tag.green { background: rgba(0, 255, 136, 0.1); color: var(--accent-green); border: 1px solid rgba(0, 255, 136, 0.2); }
.tag.purple { background: rgba(168, 85, 247, 0.1); color: var(--accent-purple); border: 1px solid rgba(168, 85, 247, 0.2); }
.tag.orange { background: rgba(255, 107, 53, 0.1); color: var(--accent-orange); border: 1px solid rgba(255, 107, 53, 0.2); }

/* ===== 章节导航卡片 ===== */
.chapter-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 1.5rem;
  margin: 2rem 0;
}

.chapter-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  padding: 1.8rem;
  text-decoration: none;
  display: block;
  transition: all 0.3s;
  position: relative;
  overflow: hidden;
}

.chapter-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0;
  width: 100%; height: 2px;
  background: linear-gradient(90deg, var(--accent-cyan), var(--accent-blue), transparent);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.3s;
}

.chapter-card:hover::before {
  transform: scaleX(1);
}

.chapter-card:hover {
  border-color: var(--accent-cyan);
  box-shadow: var(--glow-cyan);
  transform: translateY(-4px);
}

.chapter-card .num {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--accent-cyan);
  letter-spacing: 2px;
  margin-bottom: 0.8rem;
}

.chapter-card h3 {
  font-family: var(--font-display);
  font-size: 1.1rem;
  color: var(--text-primary);
  margin-bottom: 0.8rem;
}

.chapter-card p {
  font-size: 0.88rem;
  color: var(--text-muted);
  line-height: 1.6;
  margin: 0;
}

.chapter-card .topics {
  margin-top: 1rem;
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
}

.chapter-card .topic-tag {
  font-size: 0.7rem;
  font-family: var(--font-mono);
  padding: 0.2rem 0.5rem;
  background: rgba(0, 212, 255, 0.08);
  border: 1px solid rgba(0, 212, 255, 0.15);
  color: var(--text-muted);
  border-radius: 3px;
}

/* ===== 导航按钮 ===== */
.nav-buttons {
  display: flex;
  justify-content: space-between;
  margin-top: 4rem;
  padding-top: 2rem;
  border-top: 1px solid var(--border-color);
}

.nav-btn {
  display: flex;
  align-items: center;
  gap: 0.8rem;
  padding: 0.8rem 1.5rem;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  text-decoration: none;
  color: var(--text-secondary);
  font-size: 0.9rem;
  transition: all 0.2s;
}

.nav-btn:hover {
  color: var(--accent-cyan);
  border-color: var(--accent-cyan);
  box-shadow: var(--glow-cyan);
}

.nav-btn .arrow { font-size: 1.1rem; }
.nav-btn .label { font-size: 0.7rem; color: var(--text-muted); }

/* ===== 目录侧边栏 ===== */
.toc {
  position: sticky;
  top: 80px;
  max-height: calc(100vh - 100px);
  overflow-y: auto;
  scrollbar-width: thin;
  scrollbar-color: var(--border-color) transparent;
}

.toc-title {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-muted);
  letter-spacing: 2px;
  text-transform: uppercase;
  margin-bottom: 1rem;
}

.toc-list {
  list-style: none;
  padding: 0;
}

.toc-list li a {
  display: block;
  padding: 0.35rem 0;
  color: var(--text-muted);
  text-decoration: none;
  font-size: 0.85rem;
  border-left: 2px solid transparent;
  padding-left: 0.8rem;
  transition: all 0.2s;
}

.toc-list li a:hover,
.toc-list li a.active {
  color: var(--accent-cyan);
  border-left-color: var(--accent-cyan);
}

/* ===== 两列布局 ===== */
.two-col-layout {
  display: grid;
  grid-template-columns: 1fr 280px;
  gap: 3rem;
  align-items: start;
}

/* ===== 定义列表 ===== */
.def-list {
  list-style: none;
  padding: 0;
}

.def-list li {
  display: flex;
  gap: 1rem;
  padding: 0.8rem 0;
  border-bottom: 1px solid rgba(26, 58, 92, 0.5);
}

.def-list li:last-child { border-bottom: none; }

.def-list .def-term {
  font-family: var(--font-mono);
  color: var(--accent-green);
  font-size: 0.9rem;
  min-width: 160px;
  flex-shrink: 0;
}

.def-list .def-desc {
  color: var(--text-secondary);
  font-size: 0.9rem;
}

/* ===== 表格 ===== */
.data-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.9rem;
  margin: 1.5rem 0;
}

.data-table th {
  background: rgba(0, 212, 255, 0.08);
  color: var(--accent-cyan);
  font-family: var(--font-mono);
  font-size: 0.8rem;
  letter-spacing: 1px;
  padding: 0.7rem 1rem;
  text-align: left;
  border: 1px solid var(--border-color);
}

.data-table td {
  padding: 0.7rem 1rem;
  border: 1px solid var(--border-color);
  color: var(--text-secondary);
}

.data-table tr:hover td {
  background: rgba(0, 212, 255, 0.03);
}

.data-table code {
  font-size: 0.82rem;
}

/* ===== 进度条 ===== */
.progress-bar {
  height: 3px;
  background: linear-gradient(90deg, var(--accent-cyan), var(--accent-blue));
  margin-bottom: 2px;
  border-radius: 2px;
}

/* ===== 亮点块 ===== */
.highlight-block {
  background: linear-gradient(135deg, rgba(0, 212, 255, 0.05), rgba(0, 128, 255, 0.05));
  border: 1px solid rgba(0, 212, 255, 0.2);
  border-radius: 12px;
  padding: 2rem;
  margin: 2rem 0;
}

.highlight-block h3 {
  color: var(--accent-cyan);
  margin-bottom: 1rem;
  font-family: var(--font-display);
  font-size: 1.1rem;
}

/* ===== AI 专属标记 ===== */
.ai-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  background: linear-gradient(135deg, rgba(168, 85, 247, 0.15), rgba(0, 128, 255, 0.15));
  border: 1px solid rgba(168, 85, 247, 0.4);
  color: var(--accent-purple);
  font-size: 0.7rem;
  font-family: var(--font-mono);
  padding: 0.2rem 0.6rem;
  border-radius: 3px;
  letter-spacing: 1px;
  text-transform: uppercase;
  margin-left: 0.8rem;
  vertical-align: middle;
}

/* ===== 图标 ===== */
.icon {
  width: 48px; height: 48px;
  background: linear-gradient(135deg, rgba(0, 212, 255, 0.15), rgba(0, 128, 255, 0.15));
  border: 1px solid rgba(0, 212, 255, 0.2);
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.4rem;
  margin-bottom: 1rem;
}

/* ===== 滚动条 ===== */
::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--border-color); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: var(--accent-cyan); }

/* ===== 响应式 ===== */
@media (max-width: 900px) {
  .two-col-layout { grid-template-columns: 1fr; }
  .toc { display: none; }
  .compare-grid { grid-template-columns: 1fr; }
  .chapter-grid { grid-template-columns: 1fr; }
  .nav-links { display: none; }
  pre { font-size: 0.8rem; }
}

/* ===== 动画 ===== */
@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(20px); }
  to { opacity: 1; transform: translateY(0); }
}

@keyframes pulse-glow {
  0%, 100% { box-shadow: 0 0 5px rgba(0, 212, 255, 0.2); }
  50% { box-shadow: 0 0 20px rgba(0, 212, 255, 0.5); }
}

.fade-in {
  animation: fadeInUp 0.6s ease forwards;
}

/* ===== 首页特殊样式 ===== */
.hero-section {
  min-height: 80vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 2rem;
}

.hero-title {
  font-family: var(--font-display);
  font-size: clamp(2.5rem, 7vw, 5rem);
  font-weight: 900;
  line-height: 1.1;
  margin-bottom: 1.5rem;
}

.hero-title .line1 {
  display: block;
  color: var(--text-primary);
}

.hero-title .line2 {
  display: block;
  background: linear-gradient(135deg, var(--accent-cyan), var(--accent-blue));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-sub {
  font-size: 1.1rem;
  color: var(--text-secondary);
  max-width: 580px;
  margin: 0 auto 2.5rem;
  line-height: 1.8;
}

.hero-cta {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  margin-top: 2rem;
  padding: 0.9rem 2rem;
  background: linear-gradient(135deg, var(--accent-cyan), var(--accent-blue));
  color: var(--bg-primary);
  text-decoration: none;
  font-weight: 700;
  font-family: var(--font-mono);
  font-size: 0.9rem;
  letter-spacing: 1px;
  border-radius: 6px;
  transition: all 0.3s;
  box-shadow: 0 0 30px rgba(0, 212, 255, 0.3);
}

.hero-cta:hover {
  transform: translateY(-2px);
  box-shadow: 0 0 50px rgba(0, 212, 255, 0.5);
}

.stat-row {
  display: flex;
  gap: 3rem;
  margin: 3rem 0;
  flex-wrap: wrap;
  justify-content: center;
}

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

.stat-value {
  font-family: var(--font-display);
  font-size: 2rem;
  font-weight: 700;
  color: var(--accent-cyan);
  display: block;
}

.stat-label {
  font-size: 0.8rem;
  color: var(--text-muted);
  font-family: var(--font-mono);
  letter-spacing: 1px;
}

/* ===== Footer ===== */
footer {
  text-align: center;
  padding: 3rem 2rem;
  border-top: 1px solid var(--border-color);
  color: var(--text-muted);
  font-size: 0.85rem;
  font-family: var(--font-mono);
  position: relative;
  z-index: 1;
}

footer a { color: var(--accent-cyan); text-decoration: none; }