/* ============================================
   L-MATH 乐学数学 - 全局样式
   人教版小学数学学习平台
   ============================================ */

/* CSS 变量 - 设计令牌 */
:root {
  /* 主色调 - 温暖活力 */
  --primary: #FF6B35;
  --primary-light: #FF8C5A;
  --primary-dark: #E85A25;
  --primary-bg: #FFF4EE;

  /* 辅助色 */
  --secondary: #4ECDC4;
  --secondary-light: #7EDDD6;
  --secondary-dark: #3BB5AD;
  --accent: #FFE66D;
  --accent-dark: #FFD93D;

  /* 年级颜色 */
  --grade-1: #FF6B6B;
  --grade-2: #FFA94D;
  --grade-3: #FFD93D;
  --grade-4: #69DB7C;
  --grade-5: #4DABF7;
  --grade-6: #9775FA;

  /* 中性色 */
  --text-primary: #2D3436;
  --text-secondary: #636E72;
  --text-light: #B2BEC3;
  --bg-white: #FFFFFF;
  --bg-light: #F8F9FA;
  --bg-warm: #FFFBF5;
  --border: #E9ECEF;
  --border-light: #F1F3F5;

  /* 阴影 */
  --shadow-sm: 0 2px 8px rgba(0,0,0,0.06);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.08);
  --shadow-lg: 0 8px 32px rgba(0,0,0,0.12);
  --shadow-xl: 0 16px 48px rgba(0,0,0,0.16);
  --shadow-hover: 0 12px 40px rgba(255,107,53,0.2);

  /* 圆角 */
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 20px;
  --radius-xl: 28px;
  --radius-full: 9999px;

  /* 间距 */
  --space-xs: 4px;
  --space-sm: 8px;
  --space-md: 16px;
  --space-lg: 24px;
  --space-xl: 32px;
  --space-2xl: 48px;
  --space-3xl: 64px;

  /* 过渡 */
  --transition-fast: 0.15s ease;
  --transition: 0.3s ease;
  --transition-slow: 0.5s ease;

  /* 字体 */
  --font-display: 'ZCOOL KuaiLe', 'Nunito', cursive, sans-serif;
  --font-body: 'Nunito', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --font-mono: 'Fira Code', 'JetBrains Mono', monospace;
}

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

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

body {
  font-family: var(--font-body);
  color: var(--text-primary);
  background: var(--bg-white);
  line-height: 1.6;
  overflow-x: hidden;
}

a {
  text-decoration: none;
  color: inherit;
  transition: color var(--transition-fast);
}

img {
  max-width: 100%;
  display: block;
}

/* 容器 */
.container {
  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: 14px 32px;
  border-radius: var(--radius-full);
  font-family: var(--font-body);
  font-size: 1.05rem;
  font-weight: 700;
  cursor: pointer;
  border: none;
  transition: all var(--transition);
  position: relative;
  overflow: hidden;
}

.btn-primary {
  background: var(--primary);
  color: white;
  box-shadow: 0 4px 16px rgba(255,107,53,0.3);
}

.btn-primary:hover {
  background: var(--primary-dark);
  transform: translateY(-2px);
  box-shadow: var(--shadow-hover);
}

.btn-secondary {
  background: var(--bg-white);
  color: var(--primary);
  border: 2px solid var(--primary);
}

.btn-secondary:hover {
  background: var(--primary-bg);
  transform: translateY(-2px);
}

/* 章节标题 */
.section-title {
  text-align: center;
  font-family: var(--font-display);
  font-size: 2.2rem;
  color: var(--text-primary);
  margin-bottom: var(--space-md);
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-sm);
}

.title-icon {
  font-size: 1.6em;
}

.section-subtitle {
  text-align: center;
  color: var(--text-secondary);
  font-size: 1.1rem;
  margin-bottom: var(--space-2xl);
}

/* 区块间距 */
.section-grades,
.section-features,
.section-about {
  padding: var(--space-3xl) 0;
}

/* 特色区域背景 */
.section-features {
  background: var(--bg-light);
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: var(--space-lg);
}

.feature-card {
  background: var(--bg-white);
  padding: var(--space-xl);
  border-radius: var(--radius-lg);
  text-align: center;
  box-shadow: var(--shadow-sm);
  transition: all var(--transition);
  border: 1px solid var(--border-light);
}

.feature-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}

.feature-icon {
  font-size: 2.5rem;
  margin-bottom: var(--space-md);
}

.feature-card h3 {
  font-family: var(--font-display);
  font-size: 1.3rem;
  margin-bottom: var(--space-sm);
  color: var(--text-primary);
}

.feature-card p {
  color: var(--text-secondary);
  font-size: 0.95rem;
  line-height: 1.7;
}

/* 关于区域 */
.about-content {
  max-width: 720px;
  margin: 0 auto;
  text-align: center;
}

.about-content p {
  color: var(--text-secondary);
  font-size: 1.05rem;
  line-height: 1.8;
  margin-bottom: var(--space-lg);
}

/* 暗色模式 */
[data-theme="dark"] {
  --primary: #FF8C5A;
  --primary-light: #FFA878;
  --primary-dark: #FF6B35;
  --primary-bg: #3D2518;
  --text-primary: #E8E8E8;
  --text-secondary: #A0A8B0;
  --text-light: #636E72;
  --bg-white: #1A1D21;
  --bg-light: #22262B;
  --bg-warm: #1E2126;
  --border: #363A40;
  --border-light: #2C3038;
  --shadow-sm: 0 2px 8px rgba(0,0,0,0.3);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.4);
  --shadow-lg: 0 8px 32px rgba(0,0,0,0.5);
}

[data-theme="dark"] body { background: var(--bg-white); color: var(--text-primary); }
[data-theme="dark"] .navbar {
  background: rgba(26,29,33,0.92);
  border-bottom-color: var(--border);
}
[data-theme="dark"] .navbar-scrolled { background: rgba(26,29,33,0.98); }
[data-theme="dark"] .feature-card,
[data-theme="dark"] .summary-card,
[data-theme="dark"] .report-panel,
[data-theme="dark"] .mistake-card,
[data-theme="dark"] .mistake-stat {
  background: var(--bg-light);
  border-color: var(--border);
}

/* 打印样式 */
@media print {
  .navbar, .hamburger, .theme-toggle, .footer,
  .mistake-actions, .daily-actions, .report-actions,
  .modal-overlay, .btn, button { display: none !important; }
  body { background: white !important; color: black !important; }
  [data-theme="dark"] body { background: white !important; color: black !important; }
  .mistake-card, .summary-card, .report-panel,
  .daily-card, .daily-q { box-shadow: none !important; border: 1px solid #ddd !important; }
  .section-daily, .section-grades { page-break-inside: avoid; }
  a { color: inherit !important; text-decoration: none !important; }
}

/* 响应式 */
@media (max-width: 768px) {
  .section-title {
    font-size: 1.8rem;
  }

  .btn {
    padding: 12px 24px;
    font-size: 0.95rem;
  }

  .features-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 480px) {
  .container {
    padding: 0 var(--space-md);
  }

  .section-title {
    font-size: 1.5rem;
  }
}

/* 动画 */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes float {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-10px); }
}

.fade-in-up {
  animation: fadeInUp 0.6s ease forwards;
  opacity: 0;
}

/* 无障碍：减少动画偏好 */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
  .fade-in-up { opacity: 1; }
}