/* CSS Document */
/* ===== css/style.css ===== */

/* ========== 全局变量 ========== */
:root {
  --primary: #6C63FF;
  --primary-light: #8B83FF;
  --secondary: #FF6B8A;
  --accent: #FFB347;
  --accent2: #43E97B;
  --bg: #F5F7FF;
  --card-bg: #FFFFFF;
  --text: #2D3436;
  --text-light: #636E72;
  --text-lighter: #B2BEC3;
  --border: #E8ECF4;
  --shadow: 0 4px 20px rgba(108, 99, 255, 0.1);
  --shadow-hover: 0 8px 30px rgba(108, 99, 255, 0.2);
  --radius: 16px;
  --radius-sm: 10px;
  --gradient-1: linear-gradient(135deg, #6C63FF 0%, #FF6B8A 100%);
  --gradient-2: linear-gradient(135deg, #43E97B 0%, #38F9D7 100%);
  --gradient-3: linear-gradient(135deg, #FFB347 0%, #FF6B8A 100%);
  --gradient-4: linear-gradient(135deg, #6C63FF 0%, #38F9D7 100%);
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* ========== Reset & Base ========== */
* { margin: 0; padding: 0; box-sizing: border-box; }

html { scroll-behavior: smooth; font-size: 16px; }

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  min-height: 100vh;
  overflow-x: hidden;
}

a { text-decoration: none; color: inherit; }

/* ========== 顶部导航栏 ========== */
.navbar {
  position: fixed;
  top: 0; left: 0; right: 0;
  height: 64px;
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 24px;
  z-index: 1000;
  transition: var(--transition);
}

.navbar.scrolled { box-shadow: 0 2px 20px rgba(0,0,0,0.08); }

.nav-brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--primary);
}

.nav-brand .emoji { font-size: 1.5rem; }

.nav-actions { display: flex; align-items: center; gap: 12px; }

.nav-home {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 8px 16px;
  background: var(--gradient-1);
  color: #fff;
  border-radius: 20px;
  font-size: 0.85rem;
  font-weight: 600;
  transition: var(--transition);
  border: none;
  cursor: pointer;
}

.nav-home:hover { transform: translateY(-2px); box-shadow: var(--shadow-hover); }

.progress-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 14px;
  background: linear-gradient(135deg, #43E97B22, #38F9D722);
  border: 1px solid #43E97B44;
  border-radius: 20px;
  font-size: 0.8rem;
  color: #2d8659;
  font-weight: 600;
}

/* ========== 汉堡菜单（移动端） ========== */
.hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  cursor: pointer;
  padding: 4px;
  z-index: 1100;
}

.hamburger span {
  width: 24px; height: 2.5px;
  background: var(--text);
  border-radius: 2px;
  transition: var(--transition);
}

.hamburger.active span:nth-child(1) { transform: rotate(45deg) translate(5px, 5px); }
.hamburger.active span:nth-child(2) { opacity: 0; }
.hamburger.active span:nth-child(3) { transform: rotate(-45deg) translate(5px, -5px); }

/* ========== 主内容区 ========== */
.main-content { padding-top: 84px; padding-bottom: 60px; max-width: 900px; margin: 0 auto; padding-left: 20px; padding-right: 20px; }

/* ========== 首页 Hero ========== */
.hero {
  text-align: center;
  padding: 50px 20px 40px;
  background: var(--gradient-1);
  border-radius: var(--radius);
  color: #fff;
  margin-bottom: 36px;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: -50%; left: -50%;
  width: 200%; height: 200%;
  background: radial-gradient(circle, rgba(255,255,255,0.1) 0%, transparent 60%);
  animation: heroFloat 6s ease-in-out infinite;
}

@keyframes heroFloat {
  0%, 100% { transform: translate(0, 0); }
  50% { transform: translate(30px, -30px); }
}

.hero h1 { font-size: 2rem; margin-bottom: 10px; position: relative; z-index: 1; }
.hero p { font-size: 1rem; opacity: 0.9; position: relative; z-index: 1; }
.hero .subtitle { margin-top: 8px; font-size: 0.9rem; opacity: 0.8; }

/* ========== 进度总览 ========== */
.progress-overview {
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 24px;
  margin-bottom: 30px;
  box-shadow: var(--shadow);
}

.progress-overview h3 { font-size: 1.1rem; margin-bottom: 14px; display: flex; align-items: center; gap: 8px; }

.progress-bar-wrap {
  background: var(--border);
  border-radius: 10px;
  height: 14px;
  overflow: hidden;
  margin-bottom: 8px;
}

.progress-bar-fill {
  height: 100%;
  background: var(--gradient-2);
  border-radius: 10px;
  transition: width 0.6s ease;
  min-width: 0;
}

.progress-text { font-size: 0.85rem; color: var(--text-light); text-align: right; }

/* ========== 章节卡片网格 ========== */
.chapter-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 20px;
}

.chapter-card {
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 24px;
  box-shadow: var(--shadow);
  transition: var(--transition);
  cursor: pointer;
  position: relative;
  overflow: hidden;
  border: 2px solid transparent;
}

.chapter-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-hover);
  border-color: var(--primary-light);
}

.chapter-card .card-emoji { font-size: 2.2rem; margin-bottom: 12px; display: block; }

.chapter-card h3 { font-size: 1.05rem; margin-bottom: 6px; color: var(--text); }

.chapter-card .card-desc { font-size: 0.82rem; color: var(--text-light); margin-bottom: 14px; line-height: 1.5; }

.chapter-card .card-progress {
  display: flex;
  align-items: center;
  gap: 10px;
}

.card-progress-bar {
  flex: 1;
  height: 6px;
  background: var(--border);
  border-radius: 6px;
  overflow: hidden;
}

.card-progress-fill {
  height: 100%;
  background: var(--gradient-2);
  border-radius: 6px;
  transition: width 0.5s ease;
}

.card-progress-text { font-size: 0.75rem; color: var(--text-light); white-space: nowrap; }

.chapter-card .card-badge {
  position: absolute;
  top: 12px; right: 12px;
  padding: 3px 10px;
  border-radius: 12px;
  font-size: 0.7rem;
  font-weight: 600;
}

.badge-done { background: #43E97B22; color: #2d8659; }
.badge-inprogress { background: #FFB34722; color: #c77d1a; }

/* ========== 章节页面 ========== */
.chapter-header {
  background: var(--gradient-1);
  border-radius: var(--radius);
  padding: 36px 28px;
  color: #fff;
  margin-bottom: 30px;
  position: relative;
  overflow: hidden;
}

.chapter-header::after {
  content: '';
  position: absolute;
  bottom: -30px; right: -30px;
  width: 120px; height: 120px;
  background: rgba(255,255,255,0.08);
  border-radius: 50%;
}

.chapter-header .ch-num { font-size: 0.85rem; opacity: 0.8; margin-bottom: 4px; }
.chapter-header h1 { font-size: 1.7rem; margin-bottom: 8px; position: relative; z-index: 1; }
.chapter-header p { font-size: 0.9rem; opacity: 0.85; position: relative; z-index: 1; }

/* ========== 章节导航（上一章/下一章） ========== */
.chapter-nav {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  margin-top: 40px;
  margin-bottom: 20px;
}

.chapter-nav a {
  flex: 1;
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 14px 20px;
  background: var(--card-bg);
  border-radius: var(--radius-sm);
  box-shadow: var(--shadow);
  transition: var(--transition);
  font-size: 0.9rem;
  color: var(--primary);
  font-weight: 600;
}

.chapter-nav a:hover { transform: translateY(-3px); box-shadow: var(--shadow-hover); }
.chapter-nav .nav-next { justify-content: flex-end; text-align: right; }

/* ========== 考点区块 ========== */
.knowledge-section {
  background: var(--card-bg);
  border-radius: var(--radius);
  margin-bottom: 20px;
  box-shadow: var(--shadow);
  overflow: hidden;
  border: 2px solid transparent;
  transition: var(--transition);
}

.knowledge-section:hover { border-color: #6C63FF22; }

.section-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 18px 22px;
  cursor: pointer;
  user-select: none;
  transition: var(--transition);
}

.section-header:hover { background: #6C63FF08; }

.section-header .left { display: flex; align-items: center; gap: 10px; }
.section-header .left .emoji { font-size: 1.3rem; }
.section-header h3 { font-size: 1.05rem; color: var(--text); }

.section-toggle {
  width: 28px; height: 28px;
  border-radius: 50%;
  background: var(--bg);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.8rem;
  transition: var(--transition);
  color: var(--text-light);
}

.section-toggle.open { transform: rotate(180deg); background: var(--primary); color: #fff; }

.section-body { padding: 0 22px 22px; display: none; }
.section-body.open { display: block; animation: fadeIn 0.3s ease; }

@keyframes fadeIn { from { opacity: 0; transform: translateY(-8px); } to { opacity: 1; transform: translateY(0); } }

/* ========== 知识点内容 ========== */
.knowledge-point { margin-bottom: 18px; }
.knowledge-point h4 {
  font-size: 0.95rem;
  color: var(--primary);
  margin-bottom: 8px;
  display: flex;
  align-items: center;
  gap: 6px;
}

.knowledge-point p, .knowledge-point li {
  font-size: 0.9rem;
  color: var(--text);
  line-height: 1.8;
}

.knowledge-point ul, .knowledge-point ol { padding-left: 20px; margin-top: 6px; }
.knowledge-point li { margin-bottom: 4px; }

/* ========== 高亮标记 ========== */
.highlight-box {
  background: linear-gradient(135deg, #FFB34715, #FF6B8A10);
  border-left: 4px solid var(--accent);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  padding: 14px 18px;
  margin: 12px 0;
  font-size: 0.88rem;
}

.tip-box {
  background: linear-gradient(135deg, #43E97B12, #38F9D710);
  border-left: 4px solid var(--accent2);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  padding: 14px 18px;
  margin: 12px 0;
  font-size: 0.88rem;
}

.tip-box .tip-title, .highlight-box .hl-title {
  font-weight: 700;
  margin-bottom: 4px;
  display: flex;
  align-items: center;
  gap: 6px;
}

/* ========== 例题卡片 ========== */
.example-card {
  background: #F8F9FF;
  border-radius: var(--radius-sm);
  padding: 18px;
  margin: 14px 0;
  border: 1px solid var(--border);
}

.example-card .example-title {
  font-weight: 700;
  font-size: 0.9rem;
  color: var(--primary);
  margin-bottom: 8px;
  display: flex;
  align-items: center;
  gap: 6px;
}

.example-card .example-question { font-size: 0.88rem; margin-bottom: 10px; line-height: 1.7; }

.show-answer-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 8px 18px;
  background: var(--gradient-1);
  color: #fff;
  border: none;
  border-radius: 20px;
  font-size: 0.82rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
}

.show-answer-btn:hover { transform: translateY(-2px); box-shadow: var(--shadow-hover); }

.answer-content {
  display: none;
  margin-top: 12px;
  padding: 14px;
  background: #fff;
  border-radius: var(--radius-sm);
  border: 1px dashed var(--primary-light);
  font-size: 0.88rem;
  line-height: 1.7;
  animation: fadeIn 0.3s ease;
}

.answer-content.show { display: block; }

/* ========== 速记口诀 ========== */
.mnemonic-box {
  background: var(--gradient-1);
  border-radius: var(--radius);
  padding: 20px 24px;
  color: #fff;
  margin: 16px 0;
  position: relative;
  overflow: hidden;
}

.mnemonic-box::before {
  content: '💡';
  position: absolute;
  top: -10px; right: -10px;
  font-size: 4rem;
  opacity: 0.15;
}

.mnemonic-box .mn-title { font-weight: 700; margin-bottom: 8px; font-size: 0.95rem; }
.mnemonic-box p { font-size: 0.9rem; line-height: 1.8; opacity: 0.95; }

/* ========== 学习完成勾选 ========== */
.complete-check {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 14px 0;
  margin-top: 10px;
  border-top: 1px solid var(--border);
}

.complete-check input[type="checkbox"] {
  width: 20px; height: 20px;
  accent-color: var(--primary);
  cursor: pointer;
}

.complete-check label { font-size: 0.88rem; color: var(--text-light); cursor: pointer; }

/* ========== 返回顶部 ========== */
.back-to-top {
  position: fixed;
  bottom: 30px; right: 30px;
  width: 46px; height: 46px;
  background: var(--gradient-1);
  color: #fff;
  border: none;
  border-radius: 50%;
  font-size: 1.2rem;
  cursor: pointer;
  box-shadow: var(--shadow-hover);
  transition: var(--transition);
  opacity: 0;
  visibility: hidden;
  z-index: 999;
}

.back-to-top.show { opacity: 1; visibility: visible; }
.back-to-top:hover { transform: translateY(-4px) scale(1.05); }

/* ========== 表格样式 ========== */
.content-table {
  width: 100%;
  border-collapse: collapse;
  margin: 12px 0;
  font-size: 0.88rem;
  border-radius: var(--radius-sm);
  overflow: hidden;
}

.content-table thead th {
  background: var(--primary);
  color: #fff;
  padding: 10px 14px;
  text-align: left;
  font-weight: 600;
}

.content-table tbody td {
  padding: 10px 14px;
  border-bottom: 1px solid var(--border);
}

.content-table tbody tr:nth-child(even) { background: #F8F9FF; }
.content-table tbody tr:hover { background: #6C63FF08; }

/* ========== 英文高亮 ========== */
.en { font-family: 'Courier New', Courier, monospace; color: var(--primary); font-weight: 600; }
.en-light { font-family: 'Courier New', Courier, monospace; color: var(--secondary); }

/* ========== 响应式 ========== */
@media (max-width: 768px) {
  .navbar { padding: 0 16px; }
  .hamburger { display: flex; }
  .nav-actions { display: none; }
  .nav-actions.mobile-open {
    display: flex;
    flex-direction: column;
    position: fixed;
    top: 64px; left: 0; right: 0;
    background: rgba(255,255,255,0.98);
    backdrop-filter: blur(20px);
    padding: 20px;
    gap: 12px;
    border-bottom: 1px solid var(--border);
    box-shadow: 0 10px 30px rgba(0,0,0,0.1);
    animation: fadeIn 0.3s ease;
  }
  .main-content { padding-left: 16px; padding-right: 16px; padding-top: 76px; }
  .hero { padding: 36px 16px 30px; }
  .hero h1 { font-size: 1.5rem; }
  .chapter-grid { grid-template-columns: 1fr; }
  .chapter-header { padding: 28px 20px; }
  .chapter-header h1 { font-size: 1.35rem; }
  .section-header { padding: 14px 16px; }
  .section-body { padding: 0 16px 16px; }
  .chapter-nav { flex-direction: column; }
  .back-to-top { bottom: 20px; right: 20px; width: 40px; height: 40px; font-size: 1rem; }
}

@media (max-width: 480px) {
  html { font-size: 14px; }
  .chapter-card { padding: 18px; }
}