/* ============================================
   初中数学模型大全渐进式详解 — 共享样式
   ============================================ */

/* ---------- CSS 变量 ---------- */
:root {
  --bg-primary: #0a0e27;
  --bg-secondary: #111635;
  --bg-card: rgba(22, 28, 59, 0.85);
  --bg-card-hover: rgba(30, 38, 75, 0.9);
  --border-color: rgba(99, 119, 216, 0.2);
  --border-active: rgba(120, 200, 255, 0.5);

  --text-primary: #e8ecf5;
  --text-secondary: #8b94b8;
  --text-muted: #5a6285;

  --accent: #6c8eff;
  --accent-glow: rgba(108, 142, 255, 0.4);
  --accent-2: #4fd1c5;
  --accent-3: #f687b3;
  --accent-4: #fbbf24;
  --accent-5: #a78bfa;
  --accent-6: #34d399;
  --accent-7: #fb923c;
  --accent-8: #60a5fa;

  --success: #34d399;
  --warning: #fbbf24;
  --error: #f87171;

  --sidebar-w: 260px;
  --radius: 14px;
  --radius-sm: 8px;
  --shadow: 0 4px 24px rgba(0, 0, 0, 0.4);
  --shadow-glow: 0 0 30px var(--accent-glow);
  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* 章节主题色 */
[data-ch="1"]  { --theme: #6c8eff; --theme-glow: rgba(108,142,255,0.35); }
[data-ch="2"]  { --theme: #4fd1c5; --theme-glow: rgba(79,209,197,0.35); }
[data-ch="3"]  { --theme: #f687b3; --theme-glow: rgba(246,135,179,0.35); }
[data-ch="4"]  { --theme: #fbbf24; --theme-glow: rgba(251,191,36,0.35); }
[data-ch="5"]  { --theme: #a78bfa; --theme-glow: rgba(167,139,250,0.35); }
[data-ch="6"]  { --theme: #34d399; --theme-glow: rgba(52,211,153,0.35); }
[data-ch="7"]  { --theme: #fb923c; --theme-glow: rgba(251,146,60,0.35); }
[data-ch="8"]  { --theme: #60a5fa; --theme-glow: rgba(96,165,250,0.35); }

/* ---------- 基础重置 ---------- */
*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }

html { scroll-behavior: smooth; font-size: 15px; }

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
               "Microsoft YaHei", "Helvetica Neue", sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.8;
  overflow-x: hidden;
}

/* 滚动条 */
::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: rgba(108,142,255,0.3); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: rgba(108,142,255,0.5); }

a { color: var(--accent); text-decoration: none; transition: var(--transition); }
a:hover { color: var(--accent-2); }

/* ---------- 背景装饰 ---------- */
.bg-decoration {
  position: fixed; top: 0; left: 0; width: 100%; height: 100%;
  z-index: -1; pointer-events: none; overflow: hidden;
}
.bg-decoration::before, .bg-decoration::after {
  content: ''; position: absolute; border-radius: 50%; filter: blur(80px);
}
.bg-decoration::before {
  width: 500px; height: 500px; top: -100px; right: -100px;
  background: radial-gradient(circle, rgba(108,142,255,0.08), transparent);
}
.bg-decoration::after {
  width: 400px; height: 400px; bottom: -50px; left: 200px;
  background: radial-gradient(circle, rgba(79,209,197,0.06), transparent);
}

/* ---------- 侧边栏 ---------- */
.sidebar {
  position: fixed; top: 0; left: 0; width: var(--sidebar-w); height: 100vh;
  background: var(--bg-secondary); border-right: 1px solid var(--border-color);
  display: flex; flex-direction: column; z-index: 100;
  transition: transform 0.35s ease;
}
.sidebar-header {
  padding: 20px 18px 16px; border-bottom: 1px solid var(--border-color);
}
.sidebar-header .logo {
  font-size: 1.15rem; font-weight: 700; color: var(--text-primary);
  display: flex; align-items: center; gap: 8px;
}
.sidebar-header .logo .icon { font-size: 1.4rem; }
.sidebar-header .subtitle {
  font-size: 0.72rem; color: var(--text-muted); margin-top: 4px;
}

/* 进度条 */
.global-progress {
  margin: 14px 18px; padding: 10px 12px;
  background: rgba(108,142,255,0.08); border-radius: var(--radius-sm);
}
.global-progress-label {
  font-size: 0.72rem; color: var(--text-secondary);
  display: flex; justify-content: space-between; margin-bottom: 6px;
}
.global-progress-bar {
  height: 5px; background: rgba(255,255,255,0.08); border-radius: 3px; overflow: hidden;
}
.global-progress-fill {
  height: 100%; background: linear-gradient(90deg, var(--accent), var(--accent-2));
  border-radius: 3px; transition: width 0.5s ease; width: 0%;
}

/* 导航 */
.sidebar-nav { flex: 1; overflow-y: auto; padding: 8px 0; }
.nav-item {
  display: flex; align-items: center; gap: 10px;
  padding: 10px 18px; color: var(--text-secondary);
  font-size: 0.85rem; cursor: pointer; transition: var(--transition);
  border-left: 3px solid transparent; position: relative;
}
.nav-item:hover { color: var(--text-primary); background: rgba(108,142,255,0.06); }
.nav-item.active {
  color: var(--text-primary); background: rgba(108,142,255,0.1);
  border-left-color: var(--theme, var(--accent));
}
.nav-item.completed::after {
  content: '✓'; position: absolute; right: 14px; color: var(--success); font-size: 0.8rem;
}
.nav-item .ch-num {
  width: 26px; height: 26px; border-radius: 7px;
  display: flex; align-items: center; justify-content: center;
  font-size: 0.72rem; font-weight: 700; flex-shrink: 0;
  background: rgba(108,142,255,0.12); color: var(--accent);
  transition: var(--transition);
}
.nav-item.active .ch-num {
  background: var(--theme, var(--accent)); color: #fff;
}

/* ---------- 主内容区 ---------- */
.main-content {
  margin-left: var(--sidebar-w); padding: 0; min-height: 100vh;
}

/* 顶部导航栏 */
.topbar {
  position: sticky; top: 0; z-index: 50;
  display: flex; align-items: center; justify-content: space-between;
  padding: 14px 32px; background: rgba(10,14,39,0.85);
  backdrop-filter: blur(12px); border-bottom: 1px solid var(--border-color);
}
.topbar .chapter-tag {
  font-size: 0.8rem; color: var(--text-secondary);
  display: flex; align-items: center; gap: 8px;
}
.topbar .chapter-tag .dot {
  width: 8px; height: 8px; border-radius: 50%; background: var(--theme, var(--accent));
}
.topbar-nav { display: flex; gap: 10px; }
.topbar-nav a {
  padding: 6px 14px; font-size: 0.8rem; border-radius: var(--radius-sm);
  background: rgba(108,142,255,0.1); color: var(--text-secondary);
  transition: var(--transition);
}
.topbar-nav a:hover { background: rgba(108,142,255,0.2); color: var(--text-primary); }

/* ---------- 章节内容容器 ---------- */
.chapter-content { padding: 32px; max-width: 920px; margin: 0 auto; }

/* Hero 区域 */
.hero {
  text-align: center; padding: 50px 20px 40px;
  position: relative; overflow: hidden;
}
.hero::before {
  content: ''; position: absolute; top: 50%; left: 50%;
  transform: translate(-50%, -50%);
  width: 300px; height: 300px; border-radius: 50%;
  background: radial-gradient(circle, var(--theme-glow, var(--accent-glow)), transparent 70%);
  z-index: -1;
}
.hero .ch-badge {
  display: inline-block; padding: 5px 16px; border-radius: 20px;
  font-size: 0.75rem; font-weight: 600;
  background: rgba(108,142,255,0.15); color: var(--theme, var(--accent));
  border: 1px solid var(--theme, var(--accent));
  margin-bottom: 16px;
}
.hero h1 {
  font-size: 2.2rem; font-weight: 800;
  background: linear-gradient(135deg, var(--text-primary), var(--theme, var(--accent)));
  -webkit-background-clip: text; -webkit-text-fill-color: transparent;
  background-clip: text;
}
.hero .hero-subtitle {
  font-size: 0.95rem; color: var(--text-secondary); margin-top: 10px;
}
.hero .hero-emoji { font-size: 3rem; margin-bottom: 12px; display: block; }

/* ---------- 内容卡片 ---------- */
.card {
  background: var(--bg-card); border: 1px solid var(--border-color);
  border-radius: var(--radius); padding: 24px; margin-bottom: 20px;
  backdrop-filter: blur(10px); transition: var(--transition);
  position: relative; overflow: hidden;
}
.card:hover {
  border-color: var(--theme, var(--border-active));
  box-shadow: 0 4px 30px var(--theme-glow, var(--accent-glow));
}
.card::before {
  content: ''; position: absolute; top: 0; left: 0; width: 4px; height: 100%;
  background: var(--theme, var(--accent)); opacity: 0.6;
}

.card-title {
  font-size: 1.2rem; font-weight: 700; color: var(--text-primary);
  margin-bottom: 14px; display: flex; align-items: center; gap: 8px;
}
.card-title .emoji { font-size: 1.3rem; }

.card p { margin-bottom: 10px; color: var(--text-secondary); }
.card strong { color: var(--text-primary); }
.card em { color: var(--theme, var(--accent)); font-style: normal; font-weight: 600; }

/* 数学公式 */
.formula {
  display: block; text-align: center; margin: 16px auto;
  padding: 14px 20px; background: rgba(108,142,255,0.08);
  border-radius: var(--radius-sm); border: 1px solid var(--border-color);
  font-size: 1.05rem; color: var(--text-primary); overflow-x: auto;
}
.formula-inline {
  display: inline; padding: 2px 6px; background: rgba(108,142,255,0.08);
  border-radius: 4px; font-family: "Cambria Math", "Times New Roman", serif;
}

/* 提示框 */
.tip-box {
  padding: 14px 18px; margin: 14px 0; border-radius: var(--radius-sm);
  border-left: 4px solid; font-size: 0.88rem;
}
.tip-box.tip { background: rgba(52,211,153,0.08); border-color: var(--success); color: #6ee7b7; }
.tip-box.warn { background: rgba(251,191,36,0.08); border-color: var(--warning); color: #fcd34d; }
.tip-box.note { background: rgba(108,142,255,0.08); border-color: var(--accent); color: #93a8ff; }
.tip-box .tip-label { font-weight: 700; margin-right: 6px; }

/* 渐进式步骤 */
.steps { counter-reset: step; margin: 16px 0; }
.step {
  position: relative; padding: 16px 18px 16px 52px; margin-bottom: 12px;
  background: rgba(108,142,255,0.05); border-radius: var(--radius-sm);
  border: 1px solid var(--border-color); transition: var(--transition);
}
.step::before {
  counter-increment: step; content: counter(step);
  position: absolute; left: 14px; top: 14px;
  width: 26px; height: 26px; border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  font-weight: 700; font-size: 0.8rem;
  background: var(--theme, var(--accent)); color: #fff;
}
.step:hover { background: rgba(108,142,255,0.1); }
.step .step-title { font-weight: 700; color: var(--text-primary); margin-bottom: 4px; }

/* 交互组件容器 */
.interactive-box {
  background: rgba(10,14,39,0.6); border: 1px solid var(--border-color);
  border-radius: var(--radius); padding: 20px; margin: 18px 0;
  position: relative;
}
.interactive-box .ib-label {
  position: absolute; top: -10px; left: 16px;
  padding: 2px 10px; background: var(--bg-secondary);
  font-size: 0.72rem; color: var(--theme, var(--accent));
  border-radius: 4px; border: 1px solid var(--border-color);
}
.interactive-box canvas { display: block; margin: 0 auto; max-width: 100%; }

/* 滑块控件 */
.control-row {
  display: flex; align-items: center; gap: 12px; margin: 10px 0;
  flex-wrap: wrap;
}
.control-row label {
  font-size: 0.82rem; color: var(--text-secondary); min-width: 60px;
}
.control-row input[type="range"] {
  flex: 1; min-width: 120px; height: 6px;
  background: rgba(255,255,255,0.1); border-radius: 3px;
  -webkit-appearance: none; appearance: none; cursor: pointer;
}
.control-row input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none; appearance: none;
  width: 18px; height: 18px; border-radius: 50%;
  background: var(--theme, var(--accent)); cursor: pointer;
  box-shadow: 0 0 8px var(--theme-glow, var(--accent-glow));
}
.control-row .value-display {
  min-width: 50px; text-align: center; font-weight: 700;
  color: var(--theme, var(--accent)); font-size: 0.9rem;
  background: rgba(108,142,255,0.1); padding: 2px 8px; border-radius: 4px;
}

/* 按钮 */
.btn {
  display: inline-block; padding: 8px 20px; border-radius: var(--radius-sm);
  font-size: 0.85rem; font-weight: 600; cursor: pointer; border: none;
  transition: var(--transition); text-align: center;
}
.btn-primary {
  background: var(--theme, var(--accent)); color: #fff;
}
.btn-primary:hover { transform: translateY(-2px); box-shadow: 0 4px 16px var(--theme-glow, var(--accent-glow)); }
.btn-secondary {
  background: rgba(108,142,255,0.12); color: var(--text-secondary);
  border: 1px solid var(--border-color);
}
.btn-secondary:hover { background: rgba(108,142,255,0.2); color: var(--text-primary); }

/* 测验 */
.quiz {
  background: rgba(167,139,250,0.06); border: 1px solid rgba(167,139,250,0.2);
  border-radius: var(--radius); padding: 24px; margin: 20px 0;
}
.quiz-question {
  font-size: 0.95rem; color: var(--text-primary); margin-bottom: 14px;
  font-weight: 600;
}
.quiz-options { display: flex; flex-direction: column; gap: 8px; }
.quiz-option {
  padding: 10px 16px; background: rgba(108,142,255,0.06);
  border: 1px solid var(--border-color); border-radius: var(--radius-sm);
  cursor: pointer; transition: var(--transition); font-size: 0.85rem;
  color: var(--text-secondary);
}
.quiz-option:hover { background: rgba(108,142,255,0.15); color: var(--text-primary); }
.quiz-option.correct {
  background: rgba(52,211,153,0.15); border-color: var(--success); color: var(--success);
}
.quiz-option.wrong {
  background: rgba(248,113,113,0.15); border-color: var(--error); color: var(--error);
}
.quiz-feedback {
  margin-top: 12px; padding: 10px 14px; border-radius: var(--radius-sm);
  font-size: 0.82rem; display: none;
}
.quiz-feedback.show { display: block; }
.quiz-feedback.correct { background: rgba(52,211,153,0.1); color: #6ee7b7; }
.quiz-feedback.wrong { background: rgba(248,113,113,0.1); color: #fca5a5; }

/* ---------- 首页仪表盘 ---------- */
.dashboard { padding: 32px; max-width: 1100px; margin: 0 auto; }

.stats-grid {
  display: grid; grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 16px; margin-bottom: 32px;
}
.stat-card {
  background: var(--bg-card); border: 1px solid var(--border-color);
  border-radius: var(--radius); padding: 20px; text-align: center;
  transition: var(--transition); backdrop-filter: blur(10px);
}
.stat-card:hover { transform: translateY(-4px); box-shadow: var(--shadow); }
.stat-card .stat-icon { font-size: 2rem; margin-bottom: 8px; }
.stat-card .stat-value {
  font-size: 1.8rem; font-weight: 800; color: var(--theme, var(--accent));
}
.stat-card .stat-label { font-size: 0.78rem; color: var(--text-muted); }

.chapter-grid {
  display: grid; grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 18px;
}
.chapter-card {
  background: var(--bg-card); border: 1px solid var(--border-color);
  border-radius: var(--radius); padding: 24px; cursor: pointer;
  transition: var(--transition); text-decoration: none; color: inherit;
  position: relative; overflow: hidden; backdrop-filter: blur(10px);
}
.chapter-card:hover {
  transform: translateY(-6px); border-color: var(--cc-theme, var(--accent));
  box-shadow: 0 8px 32px var(--cc-glow, var(--accent-glow));
}
.chapter-card::before {
  content: ''; position: absolute; top: 0; left: 0; width: 100%; height: 3px;
  background: var(--cc-theme, var(--accent));
}
.chapter-card .cc-num {
  font-size: 0.75rem; color: var(--text-muted); font-weight: 600;
}
.chapter-card .cc-emoji { font-size: 2rem; margin: 10px 0; display: block; }
.chapter-card .cc-title {
  font-size: 1.05rem; font-weight: 700; color: var(--text-primary); margin-bottom: 6px;
}
.chapter-card .cc-desc { font-size: 0.8rem; color: var(--text-secondary); }
.chapter-card .cc-progress {
  margin-top: 12px; height: 4px; background: rgba(255,255,255,0.08);
  border-radius: 2px; overflow: hidden;
}
.chapter-card .cc-progress-fill {
  height: 100%; background: var(--cc-theme, var(--accent));
  border-radius: 2px; transition: width 0.5s ease;
}

/* ---------- 动画 ---------- */
@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(20px); }
  to { opacity: 1; transform: translateY(0); }
}
.reveal { opacity: 0; transform: translateY(20px); transition: 0.6s ease; }
.reveal.visible { opacity: 1; transform: translateY(0); }

@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.6; }
}

/* ---------- 响应式 ---------- */
@media (max-width: 900px) {
  :root { --sidebar-w: 0px; }
  .sidebar { transform: translateX(-100%); width: 260px; }
  .sidebar.open { transform: translateX(0); }
  .main-content { margin-left: 0; }
  .menu-toggle { display: flex !important; }
}

.menu-toggle {
  display: none; flex-direction: column; gap: 4px; cursor: pointer;
  padding: 6px; border-radius: 6px;
}
.menu-toggle span {
  width: 20px; height: 2px; background: var(--text-primary); border-radius: 1px;
}

/* KaTeX 调整 */
.katex { font-size: 1.05em !important; }
.katex-display { margin: 0.8em 0 !important; }