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

:root {
  --primary: #ff6b6b;
  --primary-light: #ffb3b3;
  --secondary: #4ecdc4;
  --accent: #ffe66d;
  --bg: #fff8e7;
  --text: #2d3436;
  --text-soft: #636e72;
  --white: #ffffff;
  --shadow: 0 4px 12px rgba(0,0,0,0.08);
  --shadow-lg: 0 8px 24px rgba(0,0,0,0.12);
  --radius: 16px;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  line-height: 1.6;
}

/* ===== 首页 Hero ===== */
.hero {
  text-align: center;
  padding: 60px 20px 30px;
  background: linear-gradient(135deg, #ff6b6b 0%, #4ecdc4 100%);
  color: var(--white);
  border-radius: 0 0 32px 32px;
  box-shadow: var(--shadow-lg);
}
.hero h1 { font-size: 2.4rem; margin-bottom: 8px; }
.hero .subtitle { font-size: 1.1rem; opacity: 0.9; }

/* ===== Unit 网格 ===== */
.unit-grid {
  max-width: 1200px;
  margin: 40px auto;
  padding: 0 20px;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 20px;
}
.unit-card {
  display: block;
  background: var(--white);
  padding: 24px;
  border-radius: var(--radius);
  text-decoration: none;
  color: var(--text);
  box-shadow: var(--shadow);
  transition: all 0.2s ease;
  border: 3px solid transparent;
  position: relative;
  overflow: hidden;
}
.unit-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 6px;
  background: var(--primary);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.3s;
}
.unit-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}
.unit-card:hover::before { transform: scaleX(1); }
.unit-card.highlight {
  border-color: var(--primary);
  background: linear-gradient(135deg, #fff 0%, #fff5f5 100%);
}
.unit-card.highlight::before { transform: scaleX(1); }
.unit-num {
  font-size: 0.95rem;
  color: var(--primary);
  font-weight: 700;
  margin-bottom: 4px;
  text-transform: uppercase;
  letter-spacing: 1px;
}
.unit-name {
  font-size: 1.4rem;
  font-weight: 700;
  margin-bottom: 8px;
}
.unit-meta {
  font-size: 0.95rem;
  color: var(--text-soft);
  margin-bottom: 12px;
}
.unit-time {
  display: inline-block;
  font-size: 0.85rem;
  background: var(--bg);
  color: var(--text-soft);
  padding: 4px 10px;
  border-radius: 12px;
}
.words-card .unit-num { font-size: 1.8rem; }

footer {
  text-align: center;
  padding: 40px 20px;
  color: var(--text-soft);
  font-size: 0.95rem;
}

/* ===== Unit 页面通用 ===== */
.unit-header {
  background: linear-gradient(135deg, #ff6b6b 0%, #4ecdc4 100%);
  color: var(--white);
  padding: 32px 20px;
  border-radius: 0 0 24px 24px;
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: var(--shadow-lg);
}
.unit-header h1 {
  font-size: 1.8rem;
  margin-bottom: 4px;
}
.unit-header .sub {
  font-size: 1rem;
  opacity: 0.9;
}
.unit-header .back {
  display: inline-block;
  color: var(--white);
  text-decoration: none;
  font-size: 0.9rem;
  margin-bottom: 8px;
  opacity: 0.85;
}
.unit-header .back:hover { opacity: 1; }

/* ===== Breadcrumb 面包屑 ===== */
.breadcrumb {
  background: var(--white);
  padding: 10px 20px;
  font-size: 0.85rem;
  color: var(--text-soft);
  border-bottom: 1px solid #e6eaf0;
}
.breadcrumb a { color: var(--primary-dark); text-decoration: none; font-weight: 600; }
.breadcrumb a:hover { text-decoration: underline; }
.breadcrumb .sep { margin: 0 6px; opacity: 0.5; }
.breadcrumb span:last-child { color: var(--text); font-weight: 600; }

/* ===== 阶段切换 Tab ===== */
.stage-tabs {
  display: flex;
  gap: 8px;
  padding: 20px;
  max-width: 800px;
  margin: 0 auto;
  overflow-x: auto;
}
.stage-tab {
  flex: 1;
  min-width: 80px;
  padding: 12px 16px;
  background: var(--white);
  border: 2px solid transparent;
  border-radius: 12px;
  cursor: pointer;
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-soft);
  text-align: center;
  transition: all 0.2s;
  white-space: nowrap;
}
.stage-tab:hover { transform: translateY(-2px); }
.stage-tab.active {
  background: var(--primary);
  color: var(--white);
  box-shadow: var(--shadow);
}
.stage-tab .icon { font-size: 1.4rem; display: block; margin-bottom: 4px; }

/* ===== 阶段容器 ===== */
.stage {
  display: none;
  max-width: 800px;
  margin: 0 auto;
  padding: 0 20px 40px;
}
.stage.active { display: block; }
.stage h2 {
  font-size: 1.5rem;
  color: var(--primary);
  margin-bottom: 16px;
  text-align: center;
}
.stage-intro {
  text-align: center;
  color: var(--text-soft);
  margin-bottom: 24px;
  font-size: 1.05rem;
}

/* ===== 通用音频播放器 ===== */
.audio-bar {
  background: var(--white);
  border-radius: var(--radius);
  padding: 16px 20px;
  margin-bottom: 24px;
  box-shadow: var(--shadow);
  display: flex;
  align-items: center;
  gap: 16px;
}
.play-btn {
  width: 56px;
  height: 56px;
  border-radius: 50%;
  background: var(--primary);
  color: var(--white);
  border: none;
  font-size: 1.5rem;
  cursor: pointer;
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: transform 0.15s;
}
.play-btn:hover { transform: scale(1.08); }
.play-btn:active { transform: scale(0.95); }
.play-btn.playing { background: var(--secondary); }
.audio-info { flex: 1; }
.audio-title {
  font-weight: 700;
  font-size: 1.05rem;
  margin-bottom: 4px;
}
.audio-progress {
  height: 6px;
  background: var(--bg);
  border-radius: 3px;
  overflow: hidden;
  margin-bottom: 4px;
}
.audio-progress-fill {
  height: 100%;
  background: var(--primary);
  width: 0%;
  transition: width 0.2s linear;
}
.audio-time {
  font-size: 0.85rem;
  color: var(--text-soft);
  display: flex;
  justify-content: space-between;
}

/* ===== 词卡 (Learn) ===== */
.word-card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
  gap: 12px;
  margin-bottom: 24px;
}
.word-card {
  background: var(--white);
  border-radius: var(--radius);
  padding: 20px 12px;
  text-align: center;
  cursor: pointer;
  box-shadow: var(--shadow);
  transition: all 0.2s;
  border: 2px solid transparent;
  position: relative;
  min-height: 110px;
  display: flex;
  flex-direction: column;
  justify-content: center;
}
.word-card:hover {
  transform: translateY(-3px);
  border-color: var(--primary-light);
}
.word-card .emoji { font-size: 2.4rem; display: block; margin-bottom: 6px; }
.word-card .word { font-size: 1.15rem; font-weight: 700; margin-bottom: 4px; }
.word-card .meaning { font-size: 0.85rem; color: var(--text-soft); }
.word-card .sound-btn {
  position: absolute;
  top: 8px;
  right: 8px;
  background: var(--accent);
  border: none;
  width: 30px;
  height: 30px;
  border-radius: 50%;
  font-size: 0.9rem;
  cursor: pointer;
  opacity: 0;
  transition: opacity 0.2s;
}
.word-card:hover .sound-btn { opacity: 1; }

/* ===== 闪卡游戏 (Review) ===== */
.flashcard-stage {
  background: var(--white);
  border-radius: var(--radius);
  padding: 40px 20px;
  text-align: center;
  box-shadow: var(--shadow);
  min-height: 320px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
}
.flashcard-word {
  font-size: 3rem;
  font-weight: 700;
  color: var(--primary);
  margin-bottom: 16px;
}
.flashcard-emoji {
  font-size: 5rem;
  margin-bottom: 16px;
}
.flashcard-meaning {
  font-size: 1.2rem;
  color: var(--text-soft);
  margin-bottom: 24px;
  display: none;
}
.flashcard-stage.revealed .flashcard-meaning { display: block; }
.flashcard-controls {
  display: flex;
  gap: 12px;
  margin-top: 24px;
  flex-wrap: wrap;
  justify-content: center;
}
.btn {
  padding: 12px 24px;
  border: none;
  border-radius: 24px;
  font-size: 1rem;
  font-weight: 700;
  cursor: pointer;
  transition: all 0.15s;
  display: inline-flex;
  align-items: center;
  gap: 8px;
}
.btn:hover { transform: translateY(-2px); }
.btn-primary { background: var(--primary); color: var(--white); }
.btn-secondary { background: var(--secondary); color: var(--white); }
.btn-accent { background: var(--accent); color: var(--text); }
.btn-soft { background: var(--bg); color: var(--text-soft); }

/* ===== 句型练习 (Practice) ===== */
.practice-card {
  background: var(--white);
  border-radius: var(--radius);
  padding: 24px;
  margin-bottom: 16px;
  box-shadow: var(--shadow);
}
.practice-prompt {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--text-soft);
  margin-bottom: 12px;
}
.practice-choices {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 8px;
}
.practice-choice {
  padding: 14px 16px;
  background: var(--bg);
  border: 2px solid transparent;
  border-radius: 12px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.15s;
  text-align: left;
}
.practice-choice:hover { background: var(--primary-light); }
.practice-choice.correct {
  background: #51cf66;
  color: var(--white);
  border-color: #51cf66;
}
.practice-choice.wrong {
  background: #ff6b6b;
  color: var(--white);
  border-color: #ff6b6b;
}
.practice-choice:disabled { cursor: not-allowed; }
.practice-explanation {
  margin-top: 12px;
  padding: 12px;
  background: #e7f5ff;
  border-radius: 8px;
  font-size: 0.95rem;
  color: #1971c2;
  display: none;
}
.practice-explanation.show { display: block; }

/* ===== 小游戏 (Play) ===== */
.game-board {
  background: var(--white);
  border-radius: var(--radius);
  padding: 24px;
  box-shadow: var(--shadow);
  text-align: center;
}
.game-prompt {
  font-size: 1.15rem;
  color: var(--text-soft);
  margin-bottom: 20px;
}
.game-listening-icon {
  font-size: 4rem;
  display: inline-block;
  animation: pulse 1.5s ease infinite;
  cursor: pointer;
  margin-bottom: 12px;
}
@keyframes pulse {
  0%, 100% { transform: scale(1); }
  50% { transform: scale(1.1); }
}
.game-options {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin-top: 20px;
}
.game-option {
  padding: 24px 16px;
  background: var(--bg);
  border: 3px solid transparent;
  border-radius: 16px;
  font-size: 1.4rem;
  font-weight: 700;
  cursor: pointer;
  transition: all 0.15s;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
}
.game-option:hover { background: var(--primary-light); }
.game-option.correct {
  background: #51cf66;
  color: var(--white);
  border-color: #51cf66;
  animation: shake 0.5s;
}
.game-option.wrong {
  background: #ff6b6b;
  color: var(--white);
  border-color: #ff6b6b;
  animation: shake 0.5s;
}
@keyframes shake {
  0%, 100% { transform: translateX(0); }
  25% { transform: translateX(-8px); }
  75% { transform: translateX(8px); }
}
.game-score {
  font-size: 1rem;
  color: var(--text-soft);
  margin-top: 20px;
  padding: 12px;
  background: var(--bg);
  border-radius: 8px;
}
.game-score .num {
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--primary);
}

/* ===== 跟读按钮 ===== */
.speak-btn {
  background: var(--accent);
  border: none;
  width: 50px;
  height: 50px;
  border-radius: 50%;
  font-size: 1.4rem;
  cursor: pointer;
  margin-left: 8px;
  flex-shrink: 0;
  transition: all 0.15s;
}
.speak-btn:hover { transform: scale(1.08); }
.speak-btn.recording { background: #ff6b6b; color: var(--white); animation: pulse 1s infinite; }

/* ===== 移动端 ===== */
@media (max-width: 600px) {
  .hero { padding: 40px 16px 20px; }
  .hero h1 { font-size: 1.6rem; }
  .unit-grid { grid-template-columns: 1fr 1fr; gap: 12px; padding: 0 12px; }
  .unit-card { padding: 16px 12px; }
  .unit-name { font-size: 1.1rem; }
  .unit-meta { font-size: 0.85rem; }
  .stage-tabs { padding: 12px; }
  .stage-tab { padding: 8px 10px; font-size: 0.85rem; }
  .stage-tab .icon { font-size: 1.2rem; }
  .flashcard-word { font-size: 2.4rem; }
  .flashcard-emoji { font-size: 4rem; }
  .practice-choices { grid-template-columns: 1fr; }
}