/* ============================================
   小学识字网站 - 儿童友好样式
   主色调：暖黄 + 天蓝 + 草绿
   ============================================ */

:root {
  /* 色彩系统 */
  --color-primary: #FFB347;      /* 暖橙黄 - 主色调 */
  --color-secondary: #87CEEB;   /* 天蓝色 */
  --color-success: #90EE90;      /* 浅草绿 */
  --color-danger: #FFB6C1;       /* 浅粉红 */
  --color-purple: #DDA0DD;       /* 淡紫色 */
  --color-bg: #FFF9E6;           /* 米黄背景 */
  --color-card: #FFFFFF;
  --color-text: #333333;
  --color-text-light: #666666;
  --color-border: #FFD700;

  /* 阴影 */
  --shadow-sm: 0 2px 8px rgba(0,0,0,0.1);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.12);
  --shadow-lg: 0 8px 32px rgba(0,0,0,0.15);

  /* 圆角 */
  --radius-sm: 12px;
  --radius-md: 20px;
  --radius-lg: 32px;
  --radius-full: 50px;

  /* 字体 */
  --font-main: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --font-char: "KaiTi", "STKaiti", "楷体", serif;  /* 楷体用于显示汉字 */
}

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

body {
  font-family: var(--font-main);
  background: var(--color-bg);
  color: var(--color-text);
  min-height: 100vh;
  line-height: 1.6;
}

/* ============================================
   通用组件
   ============================================ */

/* 容器 */
.container {
  max-width: 900px;
  margin: 0 auto;
  padding: 20px;
}

/* 卡片 */
.card {
  background: var(--color-card);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
  padding: 24px;
  margin-bottom: 20px;
}

/* 按钮 */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 14px 28px;
  border: none;
  border-radius: var(--radius-full);
  font-size: 18px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s ease;
  text-decoration: none;
}

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

.btn:active {
  transform: translateY(0);
}

.btn-primary {
  background: linear-gradient(135deg, var(--color-primary), #FFA500);
  color: white;
}

.btn-secondary {
  background: linear-gradient(135deg, var(--color-secondary), #5DADE2);
  color: white;
}

.btn-success {
  background: linear-gradient(135deg, var(--color-success), #32CD32);
  color: white;
}

.btn-danger {
  background: linear-gradient(135deg, var(--color-danger), #FF69B4);
  color: white;
}

.btn-large {
  padding: 20px 40px;
  font-size: 22px;
}

/* 图标按钮 */
.btn-icon {
  width: 56px;
  height: 56px;
  padding: 0;
  border-radius: 50%;
  font-size: 24px;
}

/* ============================================
   头部
   ============================================ */

.header {
  background: linear-gradient(135deg, var(--color-primary), #FF8C00);
  color: white;
  padding: 24px;
  border-radius: 0 0 var(--radius-lg) var(--radius-lg);
  margin-bottom: 30px;
  box-shadow: var(--shadow-md);
}

.header h1 {
  font-size: 28px;
  text-align: center;
  text-shadow: 2px 2px 4px rgba(0,0,0,0.2);
}

.header-subtitle {
  text-align: center;
  font-size: 16px;
  margin-top: 8px;
  opacity: 0.9;
}

/* ============================================
   主页 - 年级选择
   ============================================ */

.grade-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 24px;
  margin-top: 20px;
}

.grade-card {
  background: var(--color-card);
  border-radius: var(--radius-lg);
  padding: 32px;
  text-align: center;
  cursor: pointer;
  transition: all 0.3s ease;
  border: 4px solid transparent;
  position: relative;
  overflow: hidden;
}

.grade-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 8px;
}

.grade-card:nth-child(1)::before { background: linear-gradient(90deg, #FF6B6B, #FF8E53); }
.grade-card:nth-child(2)::before { background: linear-gradient(90deg, #4ECDC4, #45B7AA); }
.grade-card:nth-child(3)::before { background: linear-gradient(90deg, #A29BFE, #6C5CE7); }

.grade-card:hover {
  transform: translateY(-8px);
  box-shadow: var(--shadow-lg);
  border-color: var(--color-primary);
}

.grade-icon {
  font-size: 64px;
  margin-bottom: 16px;
}

.grade-title {
  font-size: 24px;
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: 8px;
}

.grade-desc {
  color: var(--color-text-light);
  font-size: 14px;
}

/* ============================================
   主页 - 分组列表
   ============================================ */

.group-list {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.group-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: var(--color-card);
  border-radius: var(--radius-md);
  padding: 20px 24px;
  cursor: pointer;
  transition: all 0.2s ease;
  border: 2px solid transparent;
}

.group-item:hover {
  transform: translateX(8px);
  border-color: var(--color-secondary);
  box-shadow: var(--shadow-sm);
}

.group-item.completed {
  border-color: var(--color-success);
  background: linear-gradient(135deg, #F0FFF0, #E8F5E8);
}

.group-info {
  display: flex;
  align-items: center;
  gap: 16px;
}

.group-number {
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--color-secondary), #5DADE2);
  color: white;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 20px;
  font-weight: 700;
}

.group-item.completed .group-number {
  background: linear-gradient(135deg, var(--color-success), #32CD32);
}

.group-name {
  font-size: 18px;
  font-weight: 600;
}

.group-progress {
  font-size: 14px;
  color: var(--color-text-light);
}

.group-arrow {
  font-size: 24px;
  color: var(--color-secondary);
}

/* 进度条 */
.progress-bar {
  height: 12px;
  background: #E8E8E8;
  border-radius: var(--radius-full);
  overflow: hidden;
  margin-top: 8px;
}

.progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--color-success), #32CD32);
  border-radius: var(--radius-full);
  transition: width 0.5s ease;
}

/* 返回按钮 */
.back-link {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  color: var(--color-text-light);
  text-decoration: none;
  font-size: 16px;
  margin-bottom: 20px;
  padding: 8px 16px;
  border-radius: var(--radius-full);
  background: var(--color-card);
  transition: all 0.2s ease;
}

.back-link:hover {
  background: var(--color-secondary);
  color: white;
}

/* ============================================
   学习页 - 单字显示
   ============================================ */

.char-display {
  text-align: center;
  padding: 40px 20px;
}

.main-char {
  font-family: var(--font-char);
  font-size: 180px;
  line-height: 1;
  color: var(--color-text);
  cursor: pointer;
  transition: all 0.2s ease;
  user-select: none;
  display: inline-block;
  animation: charAppear 0.5s ease;
}

.main-char:hover {
  transform: scale(1.05);
  color: var(--color-primary);
}

.main-char:active {
  transform: scale(0.95);
}

@keyframes charAppear {
  0% { transform: scale(0); opacity: 0; }
  50% { transform: scale(1.1); }
  100% { transform: scale(1); opacity: 1; }
}

.char-pinyin {
  font-size: 36px;
  color: var(--color-secondary);
  margin-top: 16px;
  font-weight: 600;
}

.char-audio-hint {
  font-size: 16px;
  color: var(--color-text-light);
  margin-top: 12px;
}

/* 播放按钮 */
.play-btn {
  width: 72px;
  height: 72px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--color-primary), #FF8C00);
  border: none;
  color: white;
  font-size: 32px;
  cursor: pointer;
  margin-top: 20px;
  transition: all 0.2s ease;
  box-shadow: var(--shadow-md);
  display: inline-flex;
  align-items: center;
  justify-content: center;
}

.play-btn:hover {
  transform: scale(1.1);
  box-shadow: var(--shadow-lg);
}

.play-btn:active {
  transform: scale(0.95);
}

.play-btn.playing {
  animation: pulse 1s infinite;
}

@keyframes pulse {
  0%, 100% { box-shadow: 0 0 0 0 rgba(255,179,71,0.7); }
  50% { box-shadow: 0 0 0 20px rgba(255,179,71,0); }
}

/* ============================================
   学习页 - 组词列表
   ============================================ */

.words-section {
  margin-top: 32px;
}

.section-title {
  font-size: 22px;
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: 20px;
  display: flex;
  align-items: center;
  gap: 12px;
}

.section-title::before {
  content: '';
  width: 6px;
  height: 28px;
  background: linear-gradient(180deg, var(--color-primary), #FF8C00);
  border-radius: 3px;
}

.words-list {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.word-item {
  background: linear-gradient(135deg, #FFF9E6, #FFF5E0);
  border-radius: var(--radius-md);
  padding: 20px;
  cursor: pointer;
  transition: all 0.2s ease;
  border: 2px solid transparent;
}

.word-item:hover {
  border-color: var(--color-primary);
  transform: translateX(8px);
}

.word-item.active {
  border-color: var(--color-primary);
  background: linear-gradient(135deg, #FFE8B3, #FFD98E);
}

.word-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.word-text {
  font-family: var(--font-char);
  font-size: 32px;
  font-weight: 700;
  color: var(--color-text);
}

.word-pinyin {
  font-size: 18px;
  color: var(--color-secondary);
  margin-left: 16px;
}

.word-actions {
  display: flex;
  gap: 8px;
}

.word-btn {
  width: 44px;
  height: 44px;
  border-radius: 50%;
  border: none;
  cursor: pointer;
  font-size: 20px;
  transition: all 0.2s ease;
  display: flex;
  align-items: center;
  justify-content: center;
}

.word-btn-play {
  background: var(--color-primary);
  color: white;
}

.word-btn-record {
  background: var(--color-danger);
  color: white;
}

.word-btn:hover {
  transform: scale(1.1);
}

/* 例句 */
.sentence-box {
  display: block;
  margin-top: 16px;
  padding-top: 16px;
  border-top: 2px dashed #FFE4B5;
}

.word-item.expanded .sentence-box {
  display: block;
}

.sentence-text {
  font-size: 24px;
  line-height: 2;
  color: var(--color-text);
}

.sentence-pinyin {
  font-size: 16px;
  color: var(--color-text-light);
  margin-top: 8px;
}

.sentence-audio-row {
  margin-top: 12px;
  display: flex;
  align-items: center;
  gap: 12px;
}

/* 逐字高亮 */
.char-highlight {
  transition: all 0.2s ease;
  padding: 2px 4px;
  border-radius: 4px;
}

.char-highlight.active {
  background: var(--color-primary);
  color: white;
  transform: scale(1.2);
}

/* 跟读状态 */
.record-status {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 16px;
  border-radius: var(--radius-full);
  font-size: 14px;
  font-weight: 600;
}

.record-status.idle {
  background: #E8E8E8;
  color: #666;
}

.record-status.recording {
  background: var(--color-danger);
  color: white;
  animation: blink 1s infinite;
}

.record-status.success {
  background: var(--color-success);
  color: white;
}

.record-status.error {
  background: #FFB6C1;
  color: #D32F2F;
}

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

/* ============================================
   学习页 - 关联字
   ============================================ */

.related-section {
  margin-top: 32px;
}

.related-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
  gap: 16px;
}

.related-item {
  background: linear-gradient(135deg, #E8F4FD, #D4E9F7);
  border-radius: var(--radius-md);
  padding: 20px;
  text-align: center;
  cursor: pointer;
  transition: all 0.2s ease;
  border: 2px solid transparent;
}

.related-item:hover {
  border-color: var(--color-secondary);
  transform: translateY(-4px);
}

.related-char {
  font-family: var(--font-char);
  font-size: 48px;
  font-weight: 700;
  color: var(--color-text);
}

.related-relation {
  font-size: 14px;
  color: var(--color-secondary);
  margin-top: 8px;
  font-weight: 600;
}

.related-note {
  font-size: 12px;
  color: var(--color-text-light);
  margin-top: 4px;
}

/* ============================================
   学习页 - 导航
   ============================================ */

.nav-buttons {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-top: 40px;
  padding-top: 24px;
  border-top: 2px solid #FFE4B5;
}

.nav-progress {
  font-size: 16px;
  color: var(--color-text-light);
}

.nav-progress strong {
  color: var(--color-primary);
  font-size: 24px;
}

/* ============================================
   测验页
   ============================================ */

.quiz-card {
  background: var(--color-card);
  border-radius: var(--radius-lg);
  padding: 40px;
  text-align: center;
  box-shadow: var(--shadow-md);
}

.quiz-word {
  font-family: var(--font-char);
  font-size: 72px;
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: 16px;
}

.quiz-question {
  font-size: 24px;
  color: var(--color-text-light);
  margin-bottom: 32px;
}

.quiz-options {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
  max-width: 600px;
  margin: 0 auto;
}

.quiz-option {
  padding: 20px;
  border-radius: var(--radius-md);
  background: linear-gradient(135deg, #F5F5F5, #E8E8E8);
  font-size: 28px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s ease;
  border: 3px solid transparent;
}

.quiz-option:hover:not(.disabled) {
  transform: translateY(-4px);
  box-shadow: var(--shadow-sm);
  border-color: var(--color-secondary);
}

.quiz-option.selected {
  border-color: var(--color-primary);
  background: linear-gradient(135deg, #FFF9E6, #FFE8B3);
}

.quiz-option.correct {
  border-color: var(--color-success);
  background: linear-gradient(135deg, #90EE90, #32CD32);
  color: white;
}

.quiz-option.wrong {
  border-color: var(--color-danger);
  background: linear-gradient(135deg, #FFB6C1, #FF69B4);
  color: white;
}

.quiz-option.disabled {
  cursor: not-allowed;
  opacity: 0.7;
}

/* 测验进度 */
.quiz-progress {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  margin-bottom: 32px;
}

.quiz-dot {
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: #E8E8E8;
}

.quiz-dot.current {
  background: var(--color-primary);
  transform: scale(1.3);
}

.quiz-dot.correct {
  background: var(--color-success);
}

.quiz-dot.wrong {
  background: var(--color-danger);
}

/* 测验结果 */
.quiz-result {
  text-align: center;
  padding: 40px;
}

.result-score {
  font-size: 96px;
  font-weight: 700;
  color: var(--color-primary);
  line-height: 1;
}

.result-label {
  font-size: 24px;
  color: var(--color-text-light);
  margin-top: 8px;
}

.result-message {
  font-size: 28px;
  color: var(--color-text);
  margin-top: 24px;
  font-weight: 600;
}

.result-stars {
  font-size: 48px;
  margin-top: 16px;
}

.result-actions {
  display: flex;
  justify-content: center;
  gap: 16px;
  margin-top: 32px;
}

/* ============================================
   动画效果
   ============================================ */

/* 正确反馈动画 */
.correct-burst {
  position: fixed;
  pointer-events: none;
  z-index: 1000;
}

.confetti {
  position: absolute;
  width: 10px;
  height: 10px;
  border-radius: 50%;
  animation: fall 1s ease-out forwards;
}

@keyframes fall {
  0% {
    transform: translateY(0) rotate(0deg);
    opacity: 1;
  }
  100% {
    transform: translateY(200px) rotate(720deg);
    opacity: 0;
  }
}

/* 星星动画 */
@keyframes starPop {
  0% { transform: scale(0) rotate(0deg); }
  50% { transform: scale(1.3) rotate(180deg); }
  100% { transform: scale(1) rotate(360deg); }
}

.star-pop {
  animation: starPop 0.5s ease;
}

/* ============================================
   响应式
   ============================================ */

@media (max-width: 768px) {
  .container {
    padding: 16px;
  }

  .header h1 {
    font-size: 22px;
  }

  .main-char {
    font-size: 120px;
  }

  .char-pinyin {
    font-size: 28px;
  }

  .word-text {
    font-size: 26px;
  }

  .sentence-text {
    font-size: 20px;
  }

  .quiz-options {
    grid-template-columns: 1fr;
  }

  .quiz-option {
    font-size: 24px;
  }

  .quiz-word {
    font-size: 56px;
  }

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

  .related-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

/* ============================================
   工具类
   ============================================ */

.text-center { text-align: center; }
.mt-4 { margin-top: 16px; }
.mt-6 { margin-top: 24px; }
.mb-4 { margin-bottom: 16px; }
.hidden { display: none !important; }