/* Nancy 词根词缀工坊 - 极简设计系统 */

:root {
  --color-accent: #FBBF24;
  --color-accent-dark: #F59E0B;
  --color-success: #10B981;
  --color-error: #EF4444;
  --color-text: #0F172A;
  --color-text-secondary: #64748B;
  --color-text-tertiary: #94A3B8;
  --color-bg: #FFFFFF;
  --color-bg-secondary: #F8FAFC;
  --color-border: #E2E8F0;
  --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --shadow-sm: 0 1px 2px 0 rgba(0,0,0,0.02);
  --shadow-md: 0 2px 8px 0 rgba(0,0,0,0.04);
  --shadow-lg: 0 4px 16px 0 rgba(0,0,0,0.06);
  --radius: 8px;
  --radius-lg: 12px;
  --transition: 200ms cubic-bezier(0.4,0,0.2,1);
  --space-xs: 4px;
  --space-sm: 8px;
  --space-md: 16px;
  --space-lg: 24px;
  --space-xl: 32px;
  --space-2xl: 48px;
  --space-3xl: 64px;
  --space-4xl: 96px;
}

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

html { scroll-behavior: smooth; }

body {
  font-family: var(--font-family);
  font-size: 1rem;
  line-height: 1.6;
  color: var(--color-text);
  background: var(--color-bg);
  -webkit-font-smoothing: antialiased;
}

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

/* ── 导航 ── */
.nav {
  border-bottom: 1px solid var(--color-border);
  padding: var(--space-md) 0;
  background: white;
  position: sticky;
  top: 0;
  z-index: 100;
}
.nav-container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--space-lg);
}
.nav-brand {
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--color-text);
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}
.nav-brand span { color: var(--color-accent); }
.nav-links { display: flex; gap: var(--space-xl); align-items: center; }
.nav-link {
  color: var(--color-text-secondary);
  font-weight: 500;
  font-size: 0.9rem;
  transition: var(--transition);
  padding: var(--space-xs) var(--space-sm);
  border-radius: var(--radius);
}
.nav-link:hover, .nav-link.active { color: var(--color-text); }
.nav-link.active { background: var(--color-bg-secondary); }

/* ── 容器 ── */
.container { max-width: 800px; margin: 0 auto; padding: 0 var(--space-lg); }
.container-wide { max-width: 1200px; margin: 0 auto; padding: 0 var(--space-lg); }

/* ── 按钮 ── */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  padding: 12px 24px;
  border-radius: var(--radius);
  font-weight: 600;
  font-size: 1rem;
  font-family: var(--font-family);
  transition: var(--transition);
  cursor: pointer;
  border: none;
  text-decoration: none;
}
.btn-primary {
  background: var(--color-accent);
  color: var(--color-text);
}
.btn-primary:hover {
  background: var(--color-accent-dark);
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(251,191,36,0.35);
}
.btn-secondary {
  background: transparent;
  color: var(--color-text);
  border: 1.5px solid var(--color-border);
}
.btn-secondary:hover {
  background: var(--color-bg-secondary);
  border-color: var(--color-text-tertiary);
}
.btn-large { padding: 16px 32px; font-size: 1.1rem; }
.btn-small { padding: 8px 16px; font-size: 0.875rem; }
.btn:disabled { opacity: 0.5; cursor: not-allowed; transform: none !important; }

/* ── 卡片 ── */
.card {
  background: white;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-lg);
  transition: var(--transition);
}
.card:hover {
  border-color: var(--color-accent);
  box-shadow: var(--shadow-md);
}
.card-clickable { cursor: pointer; }

/* ── 标签 ── */
.tag {
  display: inline-block;
  background: var(--color-accent);
  color: var(--color-text);
  padding: 3px 10px;
  border-radius: var(--radius);
  font-size: 0.8rem;
  font-weight: 600;
}
.tag-secondary {
  background: var(--color-bg-secondary);
  color: var(--color-text-secondary);
  border: 1px solid var(--color-border);
}
.mastered-badge {
  display: inline-block;
  background: var(--color-success);
  color: #fff;
  padding: 2px 8px;
  border-radius: var(--radius);
  font-size: 0.75rem;
  font-weight: 600;
  margin-left: var(--space-sm);
}

/* ── 进度条 ── */
.progress-bar-wrap {
  height: 6px;
  background: var(--color-bg-secondary);
  border-radius: 999px;
  overflow: hidden;
}
.progress-bar-fill {
  height: 100%;
  background: var(--color-accent);
  border-radius: 999px;
  transition: width 0.5s ease;
}

/* ── 首页 Hero ── */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-4xl) var(--space-lg);
  text-align: center;
}
.hero-inner { max-width: 760px; margin: 0 auto; }
.hero-eyebrow {
  display: inline-block;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--color-accent-dark);
  background: #FEF3C7;
  padding: 4px 14px;
  border-radius: 999px;
  margin-bottom: var(--space-lg);
  letter-spacing: 0.03em;
}
.hero-title {
  font-size: clamp(2.5rem, 6vw, 4.5rem);
  font-weight: 800;
  line-height: 1.08;
  letter-spacing: -0.03em;
  margin-bottom: var(--space-lg);
}
.hero-title .highlight { color: var(--color-accent-dark); }
.hero-subtitle {
  font-size: 1.2rem;
  color: var(--color-text-secondary);
  max-width: 520px;
  margin: 0 auto var(--space-2xl);
  line-height: 1.7;
}
.hero-cta { display: flex; gap: var(--space-md); justify-content: center; flex-wrap: wrap; }

/* ── 动画演示区 ── */
.demo-section {
  margin-top: var(--space-4xl);
  padding: var(--space-3xl) 0;
  border-top: 1px solid var(--color-border);
}
.demo-card {
  background: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-2xl);
  max-width: 560px;
  margin: var(--space-xl) auto 0;
  text-align: center;
}
.demo-word {
  font-size: 2.8rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  margin-bottom: var(--space-md);
  font-family: 'Courier New', monospace;
}
.demo-breakdown {
  display: flex;
  justify-content: center;
  gap: var(--space-sm);
  margin-bottom: var(--space-md);
  flex-wrap: wrap;
}
.demo-part {
  padding: 4px 12px;
  border-radius: var(--radius);
  font-size: 0.85rem;
  font-weight: 600;
  font-family: 'Courier New', monospace;
}
.demo-part-root { background: var(--color-accent); color: var(--color-text); }
.demo-part-affix { background: #E0E7FF; color: #4338CA; }
.demo-meaning {
  font-size: 1.05rem;
  color: var(--color-text-secondary);
}

/* ── 统计卡片 ── */
.stats-section { padding: var(--space-4xl) 0; }
.stat-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-xl);
  max-width: 720px;
  margin: 0 auto;
}
.stat-card {
  text-align: center;
  padding: var(--space-2xl) var(--space-lg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
}
.stat-value {
  font-size: 2.8rem;
  font-weight: 800;
  color: var(--color-text);
  letter-spacing: -0.03em;
  line-height: 1;
  margin-bottom: var(--space-sm);
}
.stat-label { font-size: 0.9rem; color: var(--color-text-secondary); }

/* ── 模式卡片网格 ── */
.modes-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: var(--space-lg);
  margin-top: var(--space-2xl);
}
.mode-card {
  display: block;
  padding: var(--space-xl);
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-lg);
  transition: var(--transition);
  cursor: pointer;
  text-decoration: none;
  color: var(--color-text);
}
.mode-card:hover {
  border-color: var(--color-accent);
  box-shadow: var(--shadow-md);
  transform: translateY(-3px);
}
.mode-icon { font-size: 2rem; margin-bottom: var(--space-md); }
.mode-title { font-size: 1.1rem; font-weight: 700; margin-bottom: var(--space-xs); }
.mode-desc { font-size: 0.875rem; color: var(--color-text-secondary); }

/* ── 页面头部 ── */
.page-header {
  padding: var(--space-3xl) 0 var(--space-2xl);
  border-bottom: 1px solid var(--color-border);
  margin-bottom: var(--space-2xl);
}
.page-title { font-size: 2rem; font-weight: 800; margin-bottom: var(--space-sm); }
.page-subtitle { color: var(--color-text-secondary); font-size: 1rem; }

/* ── 学习页 ── */
.learn-layout {
  display: grid;
  grid-template-columns: 1fr 320px;
  gap: var(--space-2xl);
  padding: var(--space-2xl) 0 var(--space-4xl);
  max-width: 1100px;
  margin: 0 auto;
  padding-left: var(--space-lg);
  padding-right: var(--space-lg);
}
.learn-main {}
.learn-sidebar {}
.root-header { margin-bottom: var(--space-xl); }
.root-name {
  font-size: 3rem;
  font-weight: 800;
  letter-spacing: -0.03em;
  font-family: 'Courier New', monospace;
  margin-bottom: var(--space-sm);
}
.root-meaning {
  font-size: 1.3rem;
  color: var(--color-text-secondary);
  margin-bottom: var(--space-sm);
}
.root-description {
  font-size: 1rem;
  line-height: 1.8;
  color: var(--color-text);
  margin-bottom: var(--space-2xl);
}

/* ── 例词 ── */
.examples-section { margin-bottom: var(--space-2xl); }
.section-title {
  font-size: 1rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--color-text-secondary);
  margin-bottom: var(--space-md);
}
.example-card {
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-lg);
  margin-bottom: var(--space-md);
  transition: var(--transition);
}
.example-card:hover { border-color: var(--color-accent); }
.example-word {
  font-size: 1.4rem;
  font-weight: 700;
  font-family: 'Courier New', monospace;
  margin-bottom: var(--space-xs);
}
.example-meaning {
  font-size: 0.9rem;
  color: var(--color-accent-dark);
  font-weight: 600;
  margin-bottom: var(--space-sm);
}
.example-breakdown {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-xs);
  margin-bottom: var(--space-sm);
}
.example-explanation { font-size: 0.875rem; color: var(--color-text-secondary); }

/* ── 测试题 ── */
.quiz-section { margin-bottom: var(--space-2xl); }
.quiz-question {
  font-size: 1.05rem;
  font-weight: 600;
  margin-bottom: var(--space-md);
  line-height: 1.5;
}
.quiz-options { display: flex; flex-direction: column; gap: var(--space-sm); }
.quiz-option {
  width: 100%;
  text-align: left;
  padding: 12px 16px;
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius);
  background: white;
  font-size: 0.95rem;
  font-family: var(--font-family);
  cursor: pointer;
  transition: var(--transition);
}
.quiz-option:hover:not(:disabled) {
  border-color: var(--color-accent);
  background: #FFFBEB;
}
.quiz-option.correct { border-color: var(--color-success); background: #ECFDF5; color: #065F46; }
.quiz-option.wrong { border-color: var(--color-error); background: #FEF2F2; color: #991B1B; }
.quiz-option:disabled { cursor: not-allowed; }

/* ── 导航按钮 ── */
.learn-nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-lg) 0;
  border-top: 1px solid var(--color-border);
  margin-top: var(--space-xl);
}
.learn-nav-center { font-size: 0.875rem; color: var(--color-text-secondary); }

/* ── 侧边栏 ── */
.sidebar-card {
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-lg);
  margin-bottom: var(--space-lg);
  position: sticky;
  top: 90px;
}
.sidebar-title { font-size: 0.85rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.06em; color: var(--color-text-secondary); margin-bottom: var(--space-md); }

/* ── 闪卡 ── */
.flashcard-page { padding: var(--space-2xl) 0; }
.flashcard-controls {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: var(--space-xl);
}
.flashcard-counter { font-size: 0.9rem; color: var(--color-text-secondary); }
.flashcard-wrap {
  perspective: 1000px;
  max-width: 600px;
  margin: 0 auto var(--space-xl);
  height: 360px;
  cursor: pointer;
}
.flashcard {
  width: 100%;
  height: 100%;
  position: relative;
  transform-style: preserve-3d;
  transition: transform 0.5s cubic-bezier(0.4,0,0.2,1);
}
.flashcard.flipped { transform: rotateY(180deg); }
.flashcard-front, .flashcard-back {
  position: absolute;
  width: 100%;
  height: 100%;
  backface-visibility: hidden;
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-2xl);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  background: white;
}
.flashcard-back { transform: rotateY(180deg); overflow-y: auto; }
.flashcard.flipped .flashcard-front { box-shadow: none; }
.flashcard-front:not(.flipped) { box-shadow: var(--shadow-md); }
.flashcard-root-text {
  font-size: 3.5rem;
  font-weight: 800;
  font-family: 'Courier New', monospace;
  letter-spacing: -0.02em;
  margin-bottom: var(--space-md);
}
.flashcard-meaning-text {
  font-size: 1.2rem;
  color: var(--color-text-secondary);
  margin-bottom: var(--space-md);
}
.flashcard-hint { font-size: 0.8rem; color: var(--color-text-tertiary); margin-top: var(--space-sm); }
.flashcard-back-root { font-size: 2rem; font-weight: 800; font-family: 'Courier New', monospace; margin-bottom: var(--space-sm); }
.flashcard-back-desc { font-size: 0.9rem; color: var(--color-text-secondary); line-height: 1.6; margin-bottom: var(--space-md); max-width: 440px; }
.flashcard-back-examples { display: flex; flex-wrap: wrap; gap: var(--space-sm); justify-content: center; }
.flashcard-example-tag {
  background: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 4px 12px;
  font-size: 0.8rem;
  font-family: 'Courier New', monospace;
  font-weight: 600;
}
.flashcard-keyboard-hint {
  text-align: center;
  font-size: 0.8rem;
  color: var(--color-text-tertiary);
  margin-top: var(--space-md);
}
kbd {
  background: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-radius: 4px;
  padding: 2px 6px;
  font-size: 0.75rem;
  font-family: var(--font-family);
}
.flashcard-nav {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-lg);
  margin-top: var(--space-lg);
}

/* ── 索引页 ── */
.roots-filter { display: flex; gap: var(--space-sm); flex-wrap: wrap; margin-bottom: var(--space-xl); }
.filter-btn {
  padding: 6px 16px;
  border: 1.5px solid var(--color-border);
  border-radius: 999px;
  background: white;
  font-size: 0.85rem;
  font-weight: 500;
  font-family: var(--font-family);
  cursor: pointer;
  transition: var(--transition);
  color: var(--color-text-secondary);
}
.filter-btn:hover { border-color: var(--color-accent); color: var(--color-text); }
.filter-btn.active { background: var(--color-accent); border-color: var(--color-accent); color: var(--color-text); font-weight: 700; }
.search-wrap { position: relative; margin-bottom: var(--space-lg); }
.search-input {
  width: 100%;
  padding: 12px 16px 12px 44px;
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-lg);
  font-size: 0.95rem;
  font-family: var(--font-family);
  outline: none;
  transition: var(--transition);
}
.search-input:focus { border-color: var(--color-accent); box-shadow: 0 0 0 3px rgba(251,191,36,0.15); }
.search-icon { position: absolute; left: 14px; top: 50%; transform: translateY(-50%); color: var(--color-text-tertiary); font-size: 1rem; }
.roots-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: var(--space-md);
}
.root-card {
  border: 1.5px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-lg);
  cursor: pointer;
  transition: var(--transition);
}
.root-card:hover {
  border-color: var(--color-accent);
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
}
.root-card.mastered { border-color: var(--color-success); }
.root-card-name {
  font-size: 1.3rem;
  font-weight: 800;
  font-family: 'Courier New', monospace;
  margin-bottom: var(--space-xs);
}
.root-card-meaning { font-size: 0.875rem; color: var(--color-text-secondary); margin-bottom: var(--space-sm); }
.root-card-origin { font-size: 0.8rem; }

/* ── 进度页 ── */
.progress-layout { padding: var(--space-2xl) 0; }
.progress-big {
  text-align: center;
  padding: var(--space-3xl) var(--space-lg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  margin-bottom: var(--space-2xl);
}
.progress-pct {
  font-size: 5rem;
  font-weight: 900;
  letter-spacing: -0.04em;
  line-height: 1;
  color: var(--color-text);
  margin-bottom: var(--space-sm);
}
.progress-pct span { color: var(--color-accent-dark); }
.progress-caption { color: var(--color-text-secondary); font-size: 1rem; margin-bottom: var(--space-xl); }
.mastered-list { display: grid; grid-template-columns: repeat(auto-fill, minmax(180px, 1fr)); gap: var(--space-sm); }
.mastered-item {
  padding: var(--space-sm) var(--space-md);
  background: #ECFDF5;
  border: 1px solid #A7F3D0;
  border-radius: var(--radius);
  font-size: 0.875rem;
  font-family: 'Courier New', monospace;
  font-weight: 600;
  color: #065F46;
  cursor: pointer;
}

/* ── 详情页 ── */
.detail-page { padding: var(--space-2xl) 0 var(--space-4xl); }
.detail-header {
  padding: var(--space-3xl) 0 var(--space-2xl);
  border-bottom: 1px solid var(--color-border);
  margin-bottom: var(--space-2xl);
}

/* ── Footer ── */
.footer {
  padding: var(--space-2xl) 0;
  border-top: 1px solid var(--color-border);
  margin-top: var(--space-4xl);
  text-align: center;
}
.footer-tagline { font-size: 1.1rem; font-weight: 700; margin-bottom: var(--space-sm); }
.footer-desc { font-size: 0.875rem; color: var(--color-text-secondary); max-width: 520px; margin: 0 auto; }

/* ── Toast 反馈 ── */
.feedback-toast {
  position: fixed;
  bottom: 24px;
  left: 50%;
  transform: translateX(-50%);
  padding: 12px 24px;
  border-radius: var(--radius);
  font-size: 0.9rem;
  font-weight: 600;
  z-index: 9999;
  animation: toastIn 0.3s ease;
  white-space: nowrap;
}
.feedback-toast.success { background: var(--color-success); color: white; }
.feedback-toast.error { background: var(--color-error); color: white; }
@keyframes toastIn {
  from { opacity: 0; transform: translateX(-50%) translateY(12px); }
  to { opacity: 1; transform: translateX(-50%) translateY(0); }
}

/* ── 响应式 ── */
@media (max-width: 768px) {
  .hero-title { font-size: 2.4rem; }
  .hero-subtitle { font-size: 1rem; }
  .stat-grid { grid-template-columns: 1fr; gap: var(--space-md); }
  .learn-layout { grid-template-columns: 1fr; }
  .learn-sidebar { order: -1; }
  .sidebar-card { position: static; }
  .modes-grid { grid-template-columns: 1fr 1fr; }
  .flashcard-wrap { height: 280px; }
  .flashcard-root-text { font-size: 2.5rem; }
  .nav-links { gap: var(--space-md); }
  .nav-link { font-size: 0.8rem; padding: var(--space-xs); }
}
@media (max-width: 480px) {
  .modes-grid { grid-template-columns: 1fr; }
  .hero-cta { flex-direction: column; align-items: center; }
}