/* ============================================
   导航栏
   ============================================ */
.navbar {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  height: var(--nav-height);
  background: var(--white);
  box-shadow: 0 -2px 20px rgba(0, 0, 0, 0.08);
  z-index: 1000;
  display: flex;
  align-items: center;
  justify-content: space-around;
  padding: 0 var(--space-md);
}

.navbar.hidden {
  display: none;
}

.nav-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2px;
  padding: var(--space-sm) var(--space-md);
  border-radius: var(--radius-md);
  transition: all var(--transition-normal);
  cursor: pointer;
  min-width: 64px;
  -webkit-tap-highlight-color: transparent;
}

.nav-item .nav-icon {
  font-size: 26px;
  transition: transform var(--transition-normal);
}

.nav-item .nav-label {
  font-size: var(--font-size-xs);
  font-weight: 600;
  color: var(--gray-400);
  transition: color var(--transition-normal);
}

.nav-item.active .nav-icon {
  transform: scale(1.15);
}

.nav-item.active .nav-label {
  color: var(--primary);
}

.nav-item:active {
  transform: scale(0.9);
}

body.has-navbar {
  padding-bottom: var(--nav-height);
}

/* ============================================
   课程卡片
   ============================================ */
.course-card {
  background: var(--bg-card);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-card);
  overflow: hidden;
  transition: all var(--transition-normal);
  cursor: pointer;
  position: relative;
}

.course-card:hover {
  transform: translateY(-6px) scale(1.02);
  box-shadow: var(--shadow-lg);
}

.course-card:active {
  transform: scale(0.97);
}

.course-card .card-cover {
  width: 100%;
  aspect-ratio: 16 / 10;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 56px;
  position: relative;
  overflow: hidden;
}

.course-card .card-badge {
  position: absolute;
  top: var(--space-sm);
  right: var(--space-sm);
  padding: 4px 12px;
  border-radius: var(--radius-full);
  font-size: var(--font-size-xs);
  font-weight: 700;
  color: var(--white);
}

.course-card .card-badge.video {
  background: linear-gradient(135deg, var(--primary), var(--accent-orange));
}

.course-card .card-badge.audio {
  background: linear-gradient(135deg, var(--accent-purple), var(--accent-blue));
}

.course-card .card-body {
  padding: var(--space-md);
}

.course-card .card-title {
  font-size: var(--font-size-lg);
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: var(--space-xs);
}

.course-card .card-desc {
  font-size: var(--font-size-sm);
  color: var(--text-secondary);
}

.course-card .card-count {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  margin-top: var(--space-sm);
  padding: 4px 10px;
  background: var(--gray-100);
  border-radius: var(--radius-full);
  font-size: var(--font-size-xs);
  color: var(--text-secondary);
}

/* ============================================
   分类卡片(大)
   ============================================ */
.category-card {
  background: var(--bg-card);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-card);
  padding: var(--space-xl);
  text-align: center;
  cursor: pointer;
  transition: all var(--transition-normal);
  position: relative;
  overflow: hidden;
}

.category-card::before {
  content: '';
  position: absolute;
  top: -50%;
  left: -50%;
  width: 200%;
  height: 200%;
  border-radius: 50%;
  opacity: 0.06;
  transition: opacity var(--transition-normal);
}

.category-card:hover::before {
  opacity: 0.12;
}

.category-card:hover {
  transform: translateY(-8px) scale(1.03);
  box-shadow: var(--shadow-lg);
}

.category-card:active {
  transform: scale(0.95);
}

.category-card .cat-icon {
  font-size: 56px;
  margin-bottom: var(--space-md);
  display: block;
  animation: float 3s ease-in-out infinite;
}

.category-card .cat-name {
  font-size: var(--font-size-xl);
  font-weight: 800;
  color: var(--text-primary);
  margin-bottom: var(--space-xs);
}

.category-card .cat-count {
  font-size: var(--font-size-sm);
  color: var(--text-secondary);
}

/* ============================================
   视频播放器
   ============================================ */
.video-player-wrapper {
  width: 100%;
  max-width: 900px;
  margin: 0 auto;
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-lg);
  background: #000;
  position: relative;
}

.video-player-wrapper video {
  width: 100%;
  display: block;
  background: #000;
}

.video-controls {
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  padding: var(--space-md) var(--space-lg);
  background: linear-gradient(transparent, rgba(0, 0, 0, 0.75));
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
  opacity: 0;
  transition: opacity var(--transition-normal);
}

.video-player-wrapper:hover .video-controls,
.video-player-wrapper.controls-visible .video-controls {
  opacity: 1;
}

.video-progress {
  width: 100%;
  height: 8px;
  background: rgba(255, 255, 255, 0.25);
  border-radius: var(--radius-full);
  cursor: pointer;
  position: relative;
  overflow: hidden;
}

.video-progress .progress-filled {
  height: 100%;
  background: var(--primary);
  border-radius: var(--radius-full);
  transition: width 0.1s linear;
}

.video-progress .progress-buffered {
  position: absolute;
  top: 0;
  left: 0;
  height: 100%;
  background: rgba(255, 255, 255, 0.15);
  border-radius: var(--radius-full);
}

.video-btns {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.video-btns-left,
.video-btns-right {
  display: flex;
  align-items: center;
  gap: var(--space-md);
}

.video-btns button {
  color: var(--white);
  font-size: 28px;
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  transition: all var(--transition-fast);
  background: transparent;
}

.video-btns button:hover {
  background: rgba(255, 255, 255, 0.15);
}

.video-btns button:active {
  transform: scale(0.9);
}

.video-btns .play-btn {
  font-size: 36px;
  width: 56px;
  height: 56px;
}

.video-time {
  color: rgba(255, 255, 255, 0.9);
  font-size: var(--font-size-sm);
  font-weight: 500;
  min-width: 100px;
}

.video-big-play {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 80px;
  height: 80px;
  background: rgba(255, 107, 107, 0.9);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 36px;
  color: var(--white);
  cursor: pointer;
  transition: all var(--transition-normal);
  box-shadow: 0 4px 20px rgba(255, 107, 107, 0.5);
}

.video-big-play:hover {
  transform: translate(-50%, -50%) scale(1.1);
  box-shadow: 0 6px 30px rgba(255, 107, 107, 0.6);
}

.video-big-play.hidden {
  display: none;
}

/* ============================================
   音频播放器
   ============================================ */
.audio-player-wrapper {
  width: 100%;
  max-width: 600px;
  margin: 0 auto;
  border-radius: var(--radius-xl);
  overflow: hidden;
  background: linear-gradient(135deg, var(--accent-purple), var(--accent-blue));
  box-shadow: var(--shadow-lg);
  padding: var(--space-2xl);
  text-align: center;
}

.audio-visual {
  width: 180px;
  height: 180px;
  margin: 0 auto var(--space-xl);
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.15);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 72px;
  position: relative;
}

.audio-visual.playing {
  animation: pulse 2s ease-in-out infinite;
}

.audio-visual .ring {
  position: absolute;
  border: 3px solid rgba(255, 255, 255, 0.2);
  border-radius: 50%;
  animation: none;
}

.audio-visual.playing .ring {
  animation: audioRing 2s ease-out infinite;
}

.ring-1 { width: 220px; height: 220px; animation-delay: 0s !important; }
.ring-2 { width: 260px; height: 260px; animation-delay: 0.5s !important; }
.ring-3 { width: 300px; height: 300px; animation-delay: 1s !important; }

@keyframes audioRing {
  0% { transform: scale(0.8); opacity: 1; }
  100% { transform: scale(1.2); opacity: 0; }
}

.audio-title {
  color: var(--white);
  font-size: var(--font-size-xl);
  font-weight: 700;
  margin-bottom: var(--space-lg);
}

.audio-progress {
  width: 100%;
  height: 8px;
  background: rgba(255, 255, 255, 0.25);
  border-radius: var(--radius-full);
  cursor: pointer;
  position: relative;
  margin-bottom: var(--space-sm);
}

.audio-progress .progress-filled {
  height: 100%;
  background: var(--white);
  border-radius: var(--radius-full);
  transition: width 0.1s linear;
}

.audio-time {
  display: flex;
  justify-content: space-between;
  color: rgba(255, 255, 255, 0.8);
  font-size: var(--font-size-sm);
  margin-bottom: var(--space-xl);
}

.audio-controls {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-lg);
}

.audio-controls button {
  color: var(--white);
  font-size: 28px;
  width: 56px;
  height: 56px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  transition: all var(--transition-fast);
  background: rgba(255, 255, 255, 0.1);
}

.audio-controls button:hover {
  background: rgba(255, 255, 255, 0.25);
}

.audio-controls button:active {
  transform: scale(0.9);
}

.audio-controls .audio-play-btn {
  width: 72px;
  height: 72px;
  font-size: 36px;
  background: var(--white);
  color: var(--accent-purple);
}

.audio-controls .audio-play-btn:hover {
  background: var(--white);
  transform: scale(1.1);
}

/* ============================================
   互动练习
   ============================================ */
.quiz-container {
  max-width: 700px;
  margin: 0 auto;
}

.quiz-header {
  text-align: center;
  margin-bottom: var(--space-xl);
}

.quiz-progress-bar {
  width: 100%;
  height: 12px;
  background: var(--gray-200);
  border-radius: var(--radius-full);
  overflow: hidden;
  margin-bottom: var(--space-md);
}

.quiz-progress-bar .fill {
  height: 100%;
  background: linear-gradient(90deg, var(--accent-green), var(--secondary));
  border-radius: var(--radius-full);
  transition: width var(--transition-normal);
}

.quiz-question {
  background: var(--white);
  border-radius: var(--radius-xl);
  padding: var(--space-xl);
  box-shadow: var(--shadow-card);
  margin-bottom: var(--space-lg);
  text-align: center;
}

.quiz-question .question-emoji {
  font-size: 80px;
  margin-bottom: var(--space-md);
}

.quiz-question .question-text {
  font-size: var(--font-size-xl);
  font-weight: 700;
  color: var(--text-primary);
}

.quiz-options {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-md);
}

.quiz-option {
  background: var(--white);
  border: 3px solid var(--gray-200);
  border-radius: var(--radius-lg);
  padding: var(--space-lg);
  text-align: center;
  cursor: pointer;
  transition: all var(--transition-normal);
  font-size: var(--font-size-lg);
  font-weight: 600;
}

.quiz-option:hover {
  border-color: var(--primary);
  transform: scale(1.03);
}

.quiz-option:active {
  transform: scale(0.97);
}

.quiz-option.correct {
  border-color: var(--accent-green);
  background: #E8FFF0;
  animation: bounceIn 0.4s ease;
}

.quiz-option.wrong {
  border-color: var(--primary);
  background: #FFF0F0;
  animation: shake 0.4s ease;
}

@keyframes shake {
  0%, 100% { transform: translateX(0); }
  25% { transform: translateX(-8px); }
  75% { transform: translateX(8px); }
}

.quiz-option .option-emoji {
  font-size: 48px;
  margin-bottom: var(--space-sm);
  display: block;
}

/* 练习结果 */
.quiz-result {
  text-align: center;
  padding: var(--space-2xl);
  animation: bounceIn 0.5s ease;
}

.quiz-result .result-emoji {
  font-size: 96px;
  margin-bottom: var(--space-md);
}

.quiz-result .result-title {
  font-size: var(--font-size-2xl);
  font-weight: 800;
  margin-bottom: var(--space-sm);
}

.quiz-result .result-score {
  font-size: var(--font-size-xl);
  color: var(--text-secondary);
  margin-bottom: var(--space-xl);
}

.quiz-result .stars {
  font-size: 48px;
  margin-bottom: var(--space-xl);
}

/* ============================================
   学习记录
   ============================================ */
.record-stats {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-md);
  margin-bottom: var(--space-xl);
}

.stat-card {
  background: var(--white);
  border-radius: var(--radius-lg);
  padding: var(--space-lg);
  text-align: center;
  box-shadow: var(--shadow-sm);
}

.stat-card .stat-icon {
  font-size: 36px;
  margin-bottom: var(--space-sm);
}

.stat-card .stat-value {
  font-size: var(--font-size-2xl);
  font-weight: 800;
  color: var(--text-primary);
}

.stat-card .stat-label {
  font-size: var(--font-size-sm);
  color: var(--text-secondary);
}

.record-list {
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
}

.record-item {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  background: var(--white);
  border-radius: var(--radius-lg);
  padding: var(--space-md) var(--space-lg);
  box-shadow: var(--shadow-sm);
  transition: all var(--transition-normal);
}

.record-item:hover {
  box-shadow: var(--shadow-md);
}

.record-item .record-icon {
  width: 52px;
  height: 52px;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 24px;
  flex-shrink: 0;
}

.record-item .record-info {
  flex: 1;
}

.record-item .record-title {
  font-weight: 700;
  font-size: var(--font-size-base);
  color: var(--text-primary);
}

.record-item .record-meta {
  font-size: var(--font-size-sm);
  color: var(--text-secondary);
}

.record-item .record-status {
  font-size: 24px;
}

@media (max-width: 768px) {
  .record-stats { grid-template-columns: 1fr; }
  .quiz-options { grid-template-columns: 1fr; }
  .audio-player-wrapper { padding: var(--space-lg); }
  .audio-visual { width: 140px; height: 140px; font-size: 56px; }
  .ring-1 { width: 180px; height: 180px; }
  .ring-2 { width: 210px; height: 210px; }
  .ring-3 { width: 240px; height: 240px; }
}