/**
 * Linda's English Hub — 词汇闪卡样式
 * 包含：3D翻转动画、词卡双面布局、评分按钮、进度条、完成动画
 */

/* ====== 词单选择 Tab 栏 ====== */
.deck-tabs-wrapper {
  position: relative;
  display: flex;
  align-items: center;
  margin-bottom: var(--spacing-xl);
  border-bottom: 2px solid var(--color-border-light);
}

.deck-tabs {
  display: flex;
  gap: 4px;
  overflow-x: auto;
  padding: 0 0 8px 0;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: none;
  flex: 1;
}

.deck-tabs::-webkit-scrollbar {
  display: none;
}

.deck-tabs-arrow {
  flex-shrink: 0;
  width: 32px;
  height: 32px;
  border: none;
  background: var(--color-primary-light);
  color: var(--color-primary-dark);
  border-radius: 50%;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: var(--text-sm);
  transition: background 0.2s, opacity 0.2s;
  opacity: 0.5;
}

.deck-tabs-arrow:hover {
  background: var(--color-primary);
  color: #fff;
  opacity: 1;
}

.deck-tabs-arrow:disabled {
  opacity: 0;
  pointer-events: none;
}

.deck-tabs-arrow--left {
  margin-right: var(--spacing-xs);
}

.deck-tabs-arrow--right {
  margin-left: var(--spacing-xs);
}

.deck-tab {
  flex-shrink: 0;
  padding: 0.5rem 0.875rem;
  font-size: var(--text-sm);
  font-weight: var(--weight-medium);
  color: var(--color-text-muted);
  background: transparent;
  border: 2px solid transparent;
  border-radius: var(--radius-pill);
  cursor: pointer;
  transition: all 0.2s ease;
  white-space: nowrap;
}

.deck-tab:hover {
  color: var(--color-primary);
  background: var(--color-primary-xlight);
}

.deck-tab.active {
  color: var(--color-primary-dark);
  background: var(--color-primary-light);
  border-color: var(--color-primary);
  font-weight: var(--weight-semibold);
}

.deck-tab .tab-count {
  display: inline-block;
  margin-left: 0.375rem;
  padding: 0.125rem 0.5rem;
  font-size: 0.75rem;
  background: rgba(0,0,0,0.06);
  border-radius: var(--radius-pill);
}

.deck-tab.active .tab-count {
  background: var(--color-primary);
  color: white;
}

/* ====== 模式切换 ====== */
.mode-switch {
  display: inline-flex;
  background: var(--color-primary-xlight);
  border-radius: var(--radius-pill);
  padding: 0.25rem;
  gap: 0.125rem;
}

.mode-switch button {
  padding: 0.5rem 1rem;
  font-size: var(--text-sm);
  font-weight: var(--weight-medium);
  color: var(--color-text-muted);
  background: transparent;
  border: none;
  border-radius: var(--radius-pill);
  cursor: pointer;
  transition: all 0.2s;
}

.mode-switch button.active {
  background: var(--color-primary);
  color: white;
}

/* ====== 闪卡容器 ====== */
.flashcard-scene {
  perspective: 1000px;
  width: 100%;
  max-width: 480px;
  margin: 0 auto;
}

.flashcard {
  position: relative;
  width: 100%;
  aspect-ratio: 5 / 4;
  cursor: pointer;
  transform-style: preserve-3d;
  transition: transform 0.5s cubic-bezier(0.4, 0, 0.2, 1);
}

.flashcard.flipped {
  transform: rotateY(180deg);
}

.flashcard-face {
  position: absolute;
  inset: 0;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  border-radius: var(--radius-xl);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: var(--spacing-lg);
  text-align: center;
}

/* 卡片正面 */
.flashcard-front {
  background: linear-gradient(145deg, #FFFFFF, var(--color-primary-xlight));
  border: 2px solid var(--color-primary-light);
  box-shadow:
    0 8px 30px rgba(212, 83, 126, 0.12),
    0 2px 8px rgba(0,0,0,0.04);
  z-index: 2;
}

/* 卡片背面 */
.flashcard-back {
  background: linear-gradient(145deg, #FFFFFF, #FEF5F8);
  border: 2px solid var(--color-primary-light);
  box-shadow:
    0 8px 30px rgba(212, 83, 126, 0.12),
    0 2px 8px rgba(0,0,0,0.04);
  transform: rotateY(180deg);
}

/* ====== 卡片正面内容 ====== */
.card-word {
  font-size: 1.75rem;
  font-weight: var(--weight-bold);
  color: var(--color-text-main);
  margin-bottom: 4px;
  letter-spacing: 0.02em;
  word-break: break-word;
}

.card-phonetic {
  font-size: var(--text-md);
  color: var(--color-primary);
  margin-bottom: 12px;
  font-style: italic;
}

.card-speak-btn {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: var(--color-primary);
  color: white;
  border: none;
  font-size: 0.875rem;
  cursor: pointer;
  transition: all 0.2s;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 4px 12px rgba(212, 83, 126, 0.35);
}

.card-speak-btn:hover {
  background: var(--color-primary-dark);
  transform: scale(1.08);
  box-shadow: 0 6px 18px rgba(212, 83, 126, 0.45);
}

.card-speak-btn:active {
  transform: scale(0.96);
}

.card-hint {
  margin-top: 8px;
  font-size: var(--text-xs);
  color: var(--color-text-muted);
  opacity: 0.7;
}

/* ====== 卡片背面内容 ====== */
.card-answer-section {
  width: 100%;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.card-definition {
  font-size: var(--text-lg);
  font-weight: var(--weight-semibold);
  color: var(--color-text-main);
  line-height: 1.4;
}

.card-definition .pos-tag {
  display: inline-block;
  padding: 0.2rem 0.625rem;
  background: var(--color-primary-light);
  color: var(--color-primary-dark);
  border-radius: var(--radius-sm);
  font-size: var(--text-sm);
  font-weight: var(--weight-medium);
  margin-right: 0.5rem;
}

.card-example {
  background: var(--color-primary-xlight);
  border-radius: var(--radius-lg);
  padding: 8px 12px;
  text-align: left;
}

.card-example .ex-en {
  font-size: var(--text-md);
  color: var(--color-text-main);
  line-height: 1.5;
  margin-bottom: 0.375rem;
}

.card-example .ex-cn {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
}

.card-word-review {
  font-size: var(--text-xl);
  font-weight: var(--weight-bold);
  color: var(--color-primary-dark);
  margin-bottom: var(--spacing-sm);
}

/* ====== 评分按钮组 ====== */
.rating-group {
  display: flex;
  gap: var(--spacing-md);
  margin: 16px auto 0;
  width: 100%;
  max-width: 480px;
}

.rating-btn {
  flex: 1;
  padding: 0.875rem 1rem;
  border-radius: var(--radius-lg);
  font-size: var(--text-sm);
  font-weight: var(--weight-semibold);
  border: 2px solid transparent;
  cursor: pointer;
  transition: all 0.2s;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.25rem;
}

.rating-btn .rating-icon {
  font-size: 1.25rem;
}

.rating-btn .rating-label {
  font-size: 0.75rem;
  font-weight: var(--weight-normal);
  opacity: 0.8;
}

/* 红色-不认识 */
.rating-btn.rating-unknown {
  background: var(--color-error-light);
  color: var(--color-error);
  border-color: var(--color-error-light);
}
.rating-btn.rating-unknown:hover {
  background: var(--color-error);
  color: white;
  border-color: var(--color-error);
}

/* 黄色-模糊 */
.rating-btn.rating-fuzzy {
  background: #FFF3E0;
  color: var(--color-warning);
  border-color: #FFE0B2;
}
.rating-btn.rating-fuzzy:hover {
  background: var(--color-warning);
  color: white;
  border-color: var(--color-warning);
}

/* 绿色-认识 */
.rating-btn.rating-known {
  background: #E8F5E9;
  color: var(--color-success);
  border-color: #C8E6C9;
}
.rating-btn.rating-known:hover {
  background: var(--color-success);
  color: white;
  border-color: var(--color-success);
}

.rating-btn:active {
  transform: scale(0.96);
}

/* ====== 导航控制栏 ====== */
.flashcard-controls {
  display: flex;
  align-items: center;
  justify-content: space-between;
  max-width: 480px;
  margin: 12px auto 0;
  gap: var(--spacing-sm);
}

.flashcard-controls .nav-btn {
  width: 44px;
  height: 44px;
  border-radius: 50%;
  border: 2px solid var(--color-border);
  background: white;
  color: var(--color-text-muted);
  font-size: 1rem;
  cursor: pointer;
  transition: all 0.2s;
  display: flex;
  align-items: center;
  justify-content: center;
}

.flashcard-controls .nav-btn:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
}

.flashcard-controls .nav-btn:disabled {
  opacity: 0.3;
  cursor: not-allowed;
}

.flashcard-controls .nav-btn:disabled:hover {
  border-color: var(--color-border);
  color: var(--color-text-muted);
}

.card-counter {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  font-weight: var(--weight-medium);
}

.card-counter strong {
  color: var(--color-primary-dark);
}

/* ====== 顶部信息栏 ====== */
.flashcard-topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  max-width: 480px;
  margin: 0 auto var(--spacing-md);
  gap: var(--spacing-sm);
}

.deck-progress {
  min-width: 140px;
}

.deck-progress .progress-label {
  display: flex;
  justify-content: space-between;
  font-size: var(--text-xs);
  color: var(--color-text-muted);
  margin-bottom: 0.375rem;
}

/* ====== 完成动画 ====== */
.completion-celebration {
  text-align: center;
  padding: var(--spacing-3xl) var(--spacing-xl);
}

.completion-celebration .celebration-icon {
  font-size: 4rem;
  margin-bottom: var(--spacing-lg);
  animation: bounce 0.6s ease-out;
}

.completion-celebration h2 {
  font-size: var(--text-2xl);
  color: var(--color-primary-dark);
  margin-bottom: var(--spacing-sm);
}

.completion-celebration p {
  color: var(--color-text-muted);
  margin-bottom: var(--spacing-sm);
}

.completion-stats {
  display: flex;
  gap: var(--spacing-lg);
  justify-content: center;
  margin: var(--spacing-xl) 0;
}

.completion-stat {
  text-align: center;
  background: var(--color-primary-xlight);
  border-radius: var(--radius-lg);
  padding: var(--spacing-md) var(--spacing-xl);
}

.completion-stat .stat-num {
  font-size: var(--text-2xl);
  font-weight: var(--weight-bold);
  color: var(--color-primary);
}

.completion-stat .stat-label {
  font-size: var(--text-xs);
  color: var(--color-text-muted);
  margin-top: 0.25rem;
}

@keyframes bounce {
  0%, 100% { transform: translateY(0); }
  40% { transform: translateY(-20px); }
  60% { transform: translateY(-8px); }
}

/* ====== 空状态 ====== */
.empty-state {
  text-align: center;
  padding: var(--spacing-3xl) var(--spacing-xl);
}

.empty-state .empty-icon {
  font-size: 4rem;
  display: block;
  margin-bottom: var(--spacing-md);
}

.empty-state h3 {
  font-size: var(--text-xl);
  color: var(--color-text-main);
  margin-bottom: var(--spacing-sm);
}

.empty-state p {
  color: var(--color-text-muted);
  margin-bottom: var(--spacing-lg);
}

/* ====== 单词气泡动画（完成时） ====== */
.bubble-burst {
  position: relative;
  overflow: hidden;
}

.bubble {
  position: absolute;
  border-radius: 50%;
  background: var(--color-primary-light);
  animation: float-up 2s ease-out forwards;
  opacity: 0;
}

@keyframes float-up {
  0%   { transform: translateY(0) scale(0); opacity: 0; }
  30%  { opacity: 0.8; }
  100% { transform: translateY(-200px) scale(1.5); opacity: 0; }
}

/* ====== 响应式 ====== */
@media (max-width: 768px) {
  .flashcard-scene {
    max-width: 100%;
  }

  .flashcard {
    aspect-ratio: 3 / 4.5;
  }

  .card-word {
    font-size: 2rem;
  }

  .card-definition {
    font-size: var(--text-xl);
  }

  .rating-group {
    gap: var(--spacing-sm);
  }

  .rating-btn {
    padding: 0.75rem 0.5rem;
    font-size: var(--text-xs);
  }

  .mode-switch button {
    padding: 0.375rem 0.75rem;
    font-size: var(--text-xs);
  }
}