/* ===== Flashcards Page Layout ===== */
.fc-page {
  display: flex;
  min-height: calc(100vh - 64px);
  max-width: 1400px;
  margin: 0 auto;
}

/* ===== Sidebar ===== */
.fc-sidebar {
  width: 240px;
  flex-shrink: 0;
  padding: 32px 20px;
  border-right: 1px solid #f1f5f9;
  position: sticky;
  top: 64px;
  height: calc(100vh - 64px);
  overflow-y: auto;
  background: #fafbff;
}

.fc-sidebar-header {
  margin-bottom: 24px;
}

.fc-sidebar-title {
  font-size: 18px;
  font-weight: 800;
  color: #0f172a;
  margin-bottom: 4px;
}

.fc-sidebar-desc {
  font-size: 12px;
  color: #94a3b8;
}

/* 侧边栏分区标签 */
.fc-sidebar-section-label {
  font-size: 11px;
  font-weight: 700;
  color: #94a3b8;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  padding: 0 12px;
  margin-bottom: 8px;
}

/* 主题导航 */
.fc-topic-nav {
  display: flex;
  flex-direction: column;
  gap: 6px;
  margin-bottom: 8px;
}

.fc-topic-btn {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 12px;
  border-radius: 10px;
  text-decoration: none;
  transition: all 0.2s;
  border: 1.5px solid transparent;
}

.fc-topic-btn:hover {
  background: #f1f5f9;
}

.fc-topic-btn.active {
  background: linear-gradient(135deg, rgba(99,102,241,0.08), rgba(139,92,246,0.08));
  border-color: rgba(99,102,241,0.2);
}

.fc-topic-icon {
  font-size: 20px;
  flex-shrink: 0;
  width: 28px;
  height: 28px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.fc-topic-info {
  display: flex;
  flex-direction: column;
  gap: 1px;
}

.fc-topic-name {
  font-size: 13px;
  font-weight: 600;
  color: #1e293b;
}

.fc-topic-count {
  font-size: 11px;
  color: #94a3b8;
}

.fc-sidebar-divider {
  height: 1px;
  background: #e2e8f0;
  margin: 16px 12px;
}

.fc-sidebar-nav {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.fc-sidebar-item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 12px;
  border-radius: 10px;
  font-size: 14px;
  font-weight: 500;
  color: #475569;
  text-decoration: none;
  transition: all 0.2s;
}

.fc-sidebar-item:hover {
  background: #f1f5f9;
  color: #1e293b;
}

.fc-sidebar-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  flex-shrink: 0;
}

.fc-sidebar-text {
  flex: 1;
}

.fc-sidebar-count {
  font-size: 11px;
  font-weight: 600;
  color: #94a3b8;
  background: #f1f5f9;
  padding: 2px 8px;
  border-radius: 10px;
}

/* ===== Main Content ===== */
.fc-main {
  flex: 1;
  min-width: 0;
  padding: 32px 40px;
}

/* ===== Hero / Header ===== */
.fc-hero {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 24px;
  margin-bottom: 24px;
}

.fc-hero-title {
  font-size: 28px;
  font-weight: 900;
  color: #0f172a;
  margin-bottom: 4px;
}

.fc-hero-subtitle {
  font-size: 14px;
  color: #64748b;
}

/* 移动端主题切换 tabs（PC端隐藏） */
.fc-mobile-topics {
  display: none;
  gap: 8px;
  padding: 0 4px;
  margin-bottom: 16px;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}

.fc-mobile-topic-tab {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 8px 16px;
  border-radius: 20px;
  border: 1.5px solid #e2e8f0;
  background: #fff;
  font-size: 13px;
  font-weight: 600;
  color: #64748b;
  white-space: nowrap;
  cursor: pointer;
  transition: all 0.2s;
}

.fc-mobile-topic-tab.active {
  background: linear-gradient(135deg, #6366f1, #8b5cf6);
  color: #fff;
  border-color: transparent;
  box-shadow: 0 2px 8px rgba(99,102,241,0.3);
}

.fc-mobile-topic-tab:not(.active):hover {
  border-color: #6366f1;
  color: #6366f1;
}

.fc-hero-right {
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  gap: 12px;
  flex-shrink: 0;
}

/* Progress */
.fc-progress {
  display: flex;
  align-items: center;
  gap: 12px;
}

.fc-progress-bar {
  width: 120px;
  height: 6px;
  background: #f1f5f9;
  border-radius: 3px;
  overflow: hidden;
}

.fc-progress-fill {
  height: 100%;
  background: linear-gradient(90deg, #6366f1, #8b5cf6);
  border-radius: 3px;
  transition: width 0.3s ease;
}

.fc-progress-text {
  font-size: 13px;
  font-weight: 600;
  color: #64748b;
  white-space: nowrap;
}

/* Controls */
.fc-controls {
  display: flex;
  gap: 8px;
}

.fc-filter-btn,
.fc-shuffle-btn {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 8px 16px;
  border-radius: 10px;
  font-size: 13px;
  font-weight: 600;
  font-family: inherit;
  cursor: pointer;
  transition: all 0.2s;
  border: 1px solid #e2e8f0;
  background: #fff;
  color: #475569;
}

.fc-filter-btn:hover,
.fc-shuffle-btn:hover {
  background: #f8fafc;
  border-color: #cbd5e1;
  color: #1e293b;
}

.fc-filter-btn.active {
  background: #eff6ff;
  border-color: #93c5fd;
  color: #2563eb;
}

/* ===== Filter Panel ===== */
.fc-filter-panel {
  display: none;
  background: #fff;
  border: 1px solid #e2e8f0;
  border-radius: 14px;
  padding: 20px 24px;
  margin-bottom: 24px;
  box-shadow: 0 2px 12px rgba(0, 0, 0, 0.04);
}

.fc-filter-panel.open {
  display: block;
}

.fc-filter-group {
  display: flex;
  align-items: center;
  gap: 16px;
  margin-bottom: 12px;
}

.fc-filter-group:last-child {
  margin-bottom: 0;
}

.fc-filter-label {
  font-size: 13px;
  font-weight: 600;
  color: #64748b;
  flex-shrink: 0;
  width: 40px;
}

.fc-filter-options {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.fc-filter-tag {
  padding: 6px 14px;
  border-radius: 20px;
  font-size: 12px;
  font-weight: 600;
  font-family: inherit;
  cursor: pointer;
  border: 1px solid #e2e8f0;
  background: #fff;
  color: #64748b;
  transition: all 0.2s;
}

.fc-filter-tag:hover {
  border-color: #cbd5e1;
  color: #475569;
}

.fc-filter-tag.active {
  background: #6366f1;
  border-color: #6366f1;
  color: #fff;
}

/* ===== Card Area ===== */
.fc-card-area {
  margin-bottom: 48px;
}

.fc-single-view {
  display: flex;
  align-items: center;
  gap: 16px;
  justify-content: center;
}

/* Nav Buttons */
.fc-nav-btn {
  width: 48px;
  height: 48px;
  border-radius: 50%;
  border: 1px solid #e2e8f0;
  background: #fff;
  color: #475569;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.2s;
  flex-shrink: 0;
}

.fc-nav-btn:hover:not(:disabled) {
  background: #f8fafc;
  border-color: #6366f1;
  color: #6366f1;
  box-shadow: 0 4px 12px rgba(99, 102, 241, 0.15);
}

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

/* ===== Flashcard ===== */
.fc-card-wrapper {
  perspective: 1200px;
  width: 100%;
  max-width: 600px;
}

.fc-card {
  width: 100%;
  height: 480px;
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
}

.fc-card-inner {
  position: relative;
  width: 100%;
  height: 480px;
  transition: transform 0.6s cubic-bezier(0.4, 0, 0.2, 1);
  transform-style: preserve-3d;
}

.fc-card-inner.flipped {
  transform: rotateY(180deg);
}

.fc-card-front,
.fc-card-back {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 480px;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  border-radius: 20px;
  padding: 32px;
  display: flex;
  flex-direction: column;
}

.fc-card-front {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: #fff;
  justify-content: center;
  align-items: center;
  text-align: center;
  box-shadow: 0 8px 40px rgba(102, 126, 234, 0.3);
}

.fc-card-back {
  background: #fff;
  border: 1px solid #e2e8f0;
  transform: rotateY(180deg);
  box-shadow: 0 8px 40px rgba(0, 0, 0, 0.08);
  overflow: hidden;
  height: 480px;
  min-height: 480px;
  max-height: 480px;
}

/* Card Front */
.fc-card-category {
  font-size: 12px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 1px;
  opacity: 0.85;
  background: rgba(255, 255, 255, 0.2);
  padding: 4px 14px;
  border-radius: 20px;
  margin-bottom: 24px;
}

.fc-card-question {
  font-size: 22px;
  font-weight: 800;
  line-height: 1.4;
  margin-bottom: 24px;
}

.fc-card-hint {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 12px;
  opacity: 0.6;
  margin-top: auto;
}

.fc-card-meta {
  display: flex;
  justify-content: space-between;
  width: 100%;
  margin-top: 16px;
}

.fc-card-difficulty,
.fc-card-number {
  font-size: 12px;
  font-weight: 600;
  opacity: 0.8;
}

/* Card Back */
.fc-card-back-header {
  margin-bottom: 16px;
  padding-bottom: 12px;
  border-bottom: 1px solid #f1f5f9;
  flex-shrink: 0;
}

.fc-card-back-label {
  font-size: 14px;
  font-weight: 700;
  color: #6366f1;
}

.fc-card-answer {
  font-size: 14px;
  line-height: 1.8;
  color: #334155;
  flex: 1;
  overflow-y: auto;
  min-height: 0;
  padding-right: 4px;
}

/* 答案区域滚动条美化 */
.fc-card-answer::-webkit-scrollbar {
  width: 4px;
}

.fc-card-answer::-webkit-scrollbar-track {
  background: transparent;
}

.fc-card-answer::-webkit-scrollbar-thumb {
  background: #cbd5e1;
  border-radius: 4px;
}

.fc-card-answer::-webkit-scrollbar-thumb:hover {
  background: #94a3b8;
}

.fc-card-answer strong {
  color: #0f172a;
  font-weight: 700;
}

/* Markdown 表格样式 */
.fc-card-answer table.fc-md-table {
  display: table !important;
  width: 100%;
  border-collapse: separate;
  border-spacing: 0;
  margin: 12px 0;
  font-size: 13px;
  line-height: 1.5;
  border-radius: 8px;
  border: 2px solid #cbd5e1;
  overflow: hidden;
}

.fc-card-answer table.fc-md-table th,
.fc-card-answer table.fc-md-table td {
  padding: 8px 12px;
  text-align: center;
  border-bottom: 1px solid #e2e8f0;
  border-right: 1px solid #e2e8f0;
}

.fc-card-answer table.fc-md-table th:last-child,
.fc-card-answer table.fc-md-table td:last-child {
  border-right: none;
}

.fc-card-answer table.fc-md-table tbody tr:last-child td {
  border-bottom: none;
}

.fc-card-answer table.fc-md-table thead th {
  background: #f1f5f9;
  font-weight: 700;
  color: #334155;
  font-size: 12px;
  white-space: nowrap;
  border-bottom: 2px solid #cbd5e1;
}

.fc-card-answer table.fc-md-table tbody td {
  background: #fff;
  color: #475569;
}

.fc-card-answer table.fc-md-table tbody tr:nth-child(even) td {
  background: #f8fafc;
}

.fc-card-answer table.fc-md-table tbody td:first-child {
  font-weight: 600;
  color: #334155;
  text-align: left;
  white-space: nowrap;
}

.fc-card-answer code {
  font-size: 12px;
  background: #f1f5f9;
  padding: 2px 6px;
  border-radius: 4px;
  font-family: 'SF Mono', 'Fira Code', monospace;
  color: #6366f1;
}

.fc-card-answer pre {
  background: #f8fafc;
  border: 1px solid #e2e8f0;
  border-radius: 8px;
  padding: 12px 16px;
  margin: 8px 0;
  overflow-x: auto;
}

.fc-card-answer pre code {
  background: none;
  padding: 0;
  color: #334155;
}

/* ===== References ===== */
.fc-card-refs {
  margin-top: 14px;
  padding-top: 12px;
  border-top: 1px dashed #e2e8f0;
  flex-shrink: 0;
}

.fc-refs-label {
  font-size: 12px;
  font-weight: 700;
  color: #6366f1;
  margin-bottom: 8px;
}

.fc-ref-link {
  display: block;
  font-size: 12px;
  line-height: 1.6;
  color: #475569;
  text-decoration: none;
  padding: 4px 8px;
  border-radius: 6px;
  transition: all 0.2s;
  word-break: break-word;
}

.fc-ref-link:hover {
  background: #f1f5f9;
  color: #6366f1;
}

.fc-card-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-top: 16px;
  padding-top: 12px;
  border-top: 1px solid #f1f5f9;
  flex-shrink: 0;
}

.fc-tag {
  font-size: 11px;
  font-weight: 600;
  color: #6366f1;
  background: #eff6ff;
  padding: 3px 10px;
  border-radius: 12px;
}


/* ===== Dots ===== */
.fc-dots {
  display: flex;
  justify-content: center;
  gap: 6px;
  margin-top: 20px;
  flex-wrap: wrap;
}

.fc-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  border: none;
  background: #e2e8f0;
  cursor: pointer;
  padding: 0;
  transition: all 0.2s;
}

.fc-dot:hover {
  background: #94a3b8;
}

.fc-dot.active {
  background: #6366f1;
  transform: scale(1.3);
}

/* Keyboard Hint */
.fc-keyboard-hint {
  display: flex;
  justify-content: center;
  gap: 24px;
  margin-top: 16px;
  font-size: 12px;
  color: #94a3b8;
}

.fc-keyboard-hint kbd {
  font-family: inherit;
  font-size: 11px;
  background: #f1f5f9;
  border: 1px solid #e2e8f0;
  border-radius: 4px;
  padding: 2px 6px;
  margin: 0 2px;
}

/* ===== Grid Section ===== */
.fc-grid-section {
  margin-top: 48px;
}

.fc-grid-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 20px;
}

.fc-grid-title {
  font-size: 18px;
  font-weight: 700;
  color: #0f172a;
}

.fc-grid-count {
  font-size: 13px;
  font-weight: 600;
  color: #94a3b8;
}

.fc-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 14px;
}

.fc-grid-card {
  background: #fff;
  border: 1px solid #e8ecf1;
  border-radius: 14px;
  padding: 20px;
  cursor: pointer;
  transition: all 0.25s;
  position: relative;
  overflow: hidden;
}

.fc-grid-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 4px;
  height: 100%;
  border-radius: 4px 0 0 4px;
}

.fc-grid-card.easy::before {
  background: #22c55e;
}

.fc-grid-card.medium::before {
  background: #eab308;
}

.fc-grid-card.hard::before {
  background: #ef4444;
}

.fc-grid-card:hover {
  border-color: #cbd5e1;
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.06);
  transform: translateY(-2px);
}

.fc-grid-card-top {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 10px;
}

.fc-grid-card-cat {
  font-size: 11px;
  font-weight: 600;
  color: #6366f1;
  background: #eff6ff;
  padding: 2px 10px;
  border-radius: 10px;
}

.fc-grid-card-diff {
  font-size: 11px;
}

.fc-grid-card-q {
  font-size: 14px;
  font-weight: 700;
  color: #0f172a;
  line-height: 1.5;
  margin-bottom: 12px;
}

.fc-grid-card-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
}

.fc-grid-tag {
  font-size: 10px;
  font-weight: 500;
  color: #94a3b8;
  background: #f8fafc;
  padding: 2px 8px;
  border-radius: 8px;
  border: 1px solid #f1f5f9;
}

/* ===== Pagination ===== */
.fc-pagination {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  margin-top: 28px;
  padding: 8px 0;
}

.fc-page-btn {
  min-width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 10px;
  border: 1px solid #e2e8f0;
  background: #fff;
  color: #475569;
  font-size: 13px;
  font-weight: 600;
  font-family: inherit;
  cursor: pointer;
  transition: all 0.2s;
  padding: 0 4px;
}

.fc-page-btn:hover:not(:disabled):not(.active) {
  background: #f8fafc;
  border-color: #6366f1;
  color: #6366f1;
  box-shadow: 0 2px 8px rgba(99, 102, 241, 0.12);
}

.fc-page-btn.active {
  background: #6366f1;
  border-color: #6366f1;
  color: #fff;
  box-shadow: 0 2px 8px rgba(99, 102, 241, 0.3);
}

.fc-page-btn:disabled,
.fc-page-btn.disabled {
  opacity: 0.35;
  cursor: not-allowed;
}

.fc-page-arrow {
  min-width: 36px;
}

.fc-page-ellipsis {
  min-width: 28px;
  text-align: center;
  font-size: 14px;
  color: #94a3b8;
  font-weight: 600;
  user-select: none;
}

/* ===== Responsive ===== */
@media (max-width: 900px) {
  .fc-sidebar {
    display: none;
  }

  .fc-mobile-topics {
    display: flex;
  }

  .fc-main {
    padding: 20px 16px;
  }

  .fc-hero {
    flex-direction: column;
    gap: 16px;
  }

  .fc-hero-right {
    align-items: flex-start;
    width: 100%;
  }

  .fc-hero-title {
    font-size: 22px;
  }

  .fc-single-view {
    gap: 8px;
  }

  .fc-nav-btn {
    width: 36px;
    height: 36px;
  }

  .fc-nav-btn svg {
    width: 18px;
    height: 18px;
  }

  .fc-card-wrapper {
    max-width: 100%;
  }

  .fc-card {
    height: calc(100vh - 280px);
    min-height: 360px;
    max-height: 560px;
  }

  .fc-card-inner {
    height: calc(100vh - 280px);
    min-height: 360px;
    max-height: 560px;
  }

  .fc-card-front,
  .fc-card-back {
    height: calc(100vh - 280px);
    min-height: 360px;
    max-height: 560px;
    padding: 24px;
  }

  .fc-card-question {
    font-size: 18px;
  }

  .fc-card-back {
    height: calc(100vh - 280px);
    min-height: 360px;
    max-height: 560px;
    overflow: hidden;
  }

  .fc-keyboard-hint {
    display: none;
  }

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

  .fc-filter-group {
    flex-direction: column;
    align-items: flex-start;
    gap: 8px;
  }

  .fc-filter-label {
    width: auto;
  }
}

@media (max-width: 600px) {
  .fc-hero-title {
    font-size: 20px;
  }

  .fc-card {
    height: calc(100vh - 260px);
    min-height: 400px;
    max-height: 600px;
  }

  .fc-card-inner {
    height: calc(100vh - 260px);
    min-height: 400px;
    max-height: 600px;
  }

  .fc-card-front,
  .fc-card-back {
    height: calc(100vh - 260px);
    min-height: 400px;
    max-height: 600px;
    padding: 20px;
  }

  .fc-card-question {
    font-size: 16px;
    margin-bottom: 16px;
  }

  .fc-card-category {
    margin-bottom: 16px;
  }

  .fc-card-answer {
    font-size: 13px;
    line-height: 1.7;
  }

  .fc-card-back {
    height: calc(100vh - 260px);
    min-height: 400px;
    max-height: 600px;
    overflow: hidden;
  }

  .fc-card-back-header {
    margin-bottom: 10px;
    padding-bottom: 8px;
  }

  .fc-card-refs {
    margin-top: 10px;
    padding-top: 8px;
  }

  .fc-refs-label {
    font-size: 11px;
    margin-bottom: 4px;
  }

  .fc-ref-link {
    font-size: 11px;
    padding: 2px 6px;
  }

  .fc-card-tags {
    margin-top: 10px;
    padding-top: 8px;
    gap: 4px;
  }

  .fc-tag {
    font-size: 10px;
    padding: 2px 8px;
  }

  .fc-controls {
    width: 100%;
  }

  .fc-filter-btn,
  .fc-shuffle-btn {
    flex: 1;
    justify-content: center;
  }
}