/* ===== 主题变量 ===== */
:root {
  --primary-color: #6366f1;
  --primary-light: #818cf8;
  --primary-dark: #4f46e5;
  --secondary-color: #ec4899;
  --success-color: #10b981;
  --warning-color: #f59e0b;
  --danger-color: #ef4444;
  --info-color: #06b6d4;

  --bg-body: #f8fafc;
  --bg-surface: #ffffff;
  --bg-surface-alt: #f1f5f9;
  --bg-muted: #e2e8f0;
  
  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-muted: #94a3b8;
  --text-inverse: #ffffff;
  
  --border-color: #e2e8f0;
  --border-light: #f1f5f9;
  
  --shadow-sm: 0 1px 2px 0 rgba(0,0,0,0.05);
  --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.1), 0 2px 4px -2px rgba(0,0,0,0.1);
  --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.1), 0 4px 6px -4px rgba(0,0,0,0.1);
  --shadow-xl: 0 20px 25px -5px rgba(0,0,0,0.1), 0 8px 10px -6px rgba(0,0,0,0.1);
  
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-xl: 24px;
  --radius-full: 9999px;

  --cat-keyboard: #6366f1;
  --cat-string: #ec4899;
  --cat-woodwind: #10b981;
  --cat-brass: #f59e0b;
  --cat-percussion: #ef4444;
  --cat-folk: #8b5cf6;
  --cat-electronic: #06b6d4;

  --diff-0: #64748b;
  --diff-1: #10b981;
  --diff-2: #06b6d4;
  --diff-3: #6366f1;
  --diff-4: #f59e0b;
  --diff-5: #ef4444;

  --transition-fast: 150ms ease;
  --transition-normal: 300ms ease;
  --transition-slow: 500ms ease;

  --header-height: 64px;
  --container-max: 1200px;
}

[data-theme="dark"] {
  --bg-body: #0f172a;
  --bg-surface: #1e293b;
  --bg-surface-alt: #334155;
  --bg-muted: #475569;
  
  --text-primary: #f1f5f9;
  --text-secondary: #cbd5e1;
  --text-muted: #64748b;
  --text-inverse: #0f172a;
  
  --border-color: #334155;
  --border-light: #1e293b;
  
  --shadow-sm: 0 1px 2px 0 rgba(0,0,0,0.3);
  --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.4), 0 2px 4px -2px rgba(0,0,0,0.3);
  --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.4), 0 4px 6px -4px rgba(0,0,0,0.3);
  --shadow-xl: 0 20px 25px -5px rgba(0,0,0,0.4), 0 8px 10px -6px rgba(0,0,0,0.3);
}

/* ===== 基础样式 ===== */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

.container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 24px;
  width: 100%;
}

a {
  color: inherit;
  text-decoration: none;
}

button {
  font-family: inherit;
  cursor: pointer;
  border: none;
  background: none;
  color: inherit;
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

input, select {
  font-family: inherit;
  font-size: inherit;
}

/* ===== 头部 ===== */
.site-header {
  background: var(--bg-surface);
  border-bottom: 1px solid var(--border-color);
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--header-height);
  backdrop-filter: saturate(180%) blur(10px);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
}

.logo {
  display: flex;
  align-items: center;
  gap: 12px;
}

.logo-icon {
  font-size: 28px;
}

.logo-text {
  font-size: 20px;
  font-weight: 700;
  background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 12px;
}

.btn-icon {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-full);
  background: var(--bg-surface-alt);
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  transition: all var(--transition-fast);
  font-size: 18px;
}

.btn-icon:hover {
  background: var(--bg-muted);
  transform: translateY(-1px);
}

.theme-icon-light { display: inline; }
.theme-icon-dark { display: none; }
[data-theme="dark"] .theme-icon-light { display: none; }
[data-theme="dark"] .theme-icon-dark { display: inline; }

.badge {
  position: absolute;
  top: -4px;
  right: -4px;
  min-width: 20px;
  height: 20px;
  border-radius: var(--radius-full);
  background: var(--danger-color);
  color: white;
  font-size: 11px;
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0 6px;
}

/* ===== Hero Section ===== */
.hero-section {
  padding: 48px 0 32px;
  background: linear-gradient(135deg, rgba(99, 102, 241, 0.1), rgba(236, 72, 153, 0.1));
}

.hero-title {
  font-size: 36px;
  font-weight: 800;
  text-align: center;
  margin-bottom: 12px;
  color: var(--text-primary);
}

.hero-subtitle {
  font-size: 16px;
  text-align: center;
  color: var(--text-secondary);
  margin-bottom: 32px;
}

.search-box {
  max-width: 640px;
  margin: 0 auto;
  position: relative;
  display: flex;
  align-items: center;
  background: var(--bg-surface);
  border: 2px solid var(--border-color);
  border-radius: var(--radius-xl);
  padding: 4px 4px 4px 16px;
  box-shadow: var(--shadow-md);
  transition: all var(--transition-normal);
}

.search-box:focus-within {
  border-color: var(--primary-color);
  box-shadow: 0 0 0 4px rgba(99, 102, 241, 0.1), var(--shadow-lg);
}

.search-icon {
  font-size: 18px;
  color: var(--text-muted);
  margin-right: 12px;
  flex-shrink: 0;
}

#searchInput {
  flex: 1;
  border: none;
  outline: none;
  padding: 12px 8px;
  background: transparent;
  font-size: 15px;
  color: var(--text-primary);
  min-width: 0;
}

#searchInput::placeholder {
  color: var(--text-muted);
}

.search-clear {
  width: 32px;
  height: 32px;
  border-radius: var(--radius-full);
  background: var(--bg-surface-alt);
  color: var(--text-muted);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 12px;
  transition: all var(--transition-fast);
  flex-shrink: 0;
}

.search-clear:hover {
  background: var(--bg-muted);
  color: var(--text-primary);
}

/* ===== 筛选区域 ===== */
.filter-section {
  padding: 24px 0;
  background: var(--bg-surface);
  border-bottom: 1px solid var(--border-color);
}

.filter-group {
  margin-bottom: 16px;
}

.filter-group:last-of-type {
  margin-bottom: 0;
}

.filter-label {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 14px;
  font-weight: 600;
  color: var(--text-secondary);
  margin-bottom: 10px;
}

.tab-group {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.tab-btn {
  padding: 8px 16px;
  border-radius: var(--radius-full);
  background: var(--bg-surface-alt);
  color: var(--text-secondary);
  font-size: 13px;
  font-weight: 500;
  transition: all var(--transition-fast);
  border: 1px solid transparent;
}

.tab-btn:hover {
  background: var(--bg-muted);
  color: var(--text-primary);
}

.tab-btn.active {
  background: var(--primary-color);
  color: white;
  box-shadow: 0 2px 8px rgba(99, 102, 241, 0.3);
}

.tab-btn[data-cat="keyboard"].active { background: var(--cat-keyboard); box-shadow: 0 2px 8px rgba(99,102,241,0.3); }
.tab-btn[data-cat="string"].active { background: var(--cat-string); box-shadow: 0 2px 8px rgba(236,72,153,0.3); }
.tab-btn[data-cat="woodwind"].active { background: var(--cat-woodwind); box-shadow: 0 2px 8px rgba(16,185,129,0.3); }
.tab-btn[data-cat="brass"].active { background: var(--cat-brass); box-shadow: 0 2px 8px rgba(245,158,11,0.3); }
.tab-btn[data-cat="percussion"].active { background: var(--cat-percussion); box-shadow: 0 2px 8px rgba(239,68,68,0.3); }
.tab-btn[data-cat="folk"].active { background: var(--cat-folk); box-shadow: 0 2px 8px rgba(139,92,246,0.3); }
.tab-btn[data-cat="electronic"].active { background: var(--cat-electronic); box-shadow: 0 2px 8px rgba(6,182,212,0.3); }

.filter-footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-top: 20px;
  padding-top: 16px;
  border-top: 1px solid var(--border-light);
}

.result-count {
  font-size: 14px;
  color: var(--text-muted);
  font-weight: 500;
}

.result-count strong {
  color: var(--primary-color);
  font-weight: 700;
}

.sort-group {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 14px;
  color: var(--text-secondary);
}

#sortSelect {
  padding: 6px 12px;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
  background: var(--bg-surface);
  color: var(--text-primary);
  font-size: 13px;
  cursor: pointer;
  transition: border-color var(--transition-fast);
}

#sortSelect:hover, #sortSelect:focus {
  border-color: var(--primary-color);
  outline: none;
}

/* ===== 主内容 ===== */
.main-content {
  padding: 32px 0 64px;
  min-height: 400px;
}

.state-container {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 80px 24px;
  text-align: center;
}

.loading-spinner {
  width: 48px;
  height: 48px;
  border: 4px solid var(--bg-muted);
  border-top-color: var(--primary-color);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
  margin-bottom: 20px;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

.state-icon {
  font-size: 64px;
  margin-bottom: 16px;
  opacity: 0.8;
}

.state-title {
  font-size: 20px;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 8px;
}

.state-desc {
  font-size: 14px;
  color: var(--text-muted);
  margin-bottom: 24px;
}

.btn-primary {
  padding: 10px 24px;
  background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
  color: white;
  border-radius: var(--radius-md);
  font-size: 14px;
  font-weight: 600;
  transition: all var(--transition-fast);
  box-shadow: 0 2px 8px rgba(99, 102, 241, 0.3);
}

.btn-primary:hover {
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(99, 102, 241, 0.4);
}

/* ===== 卡片网格 ===== */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 20px;
}

.instrument-card {
  background: var(--bg-surface);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  transition: all var(--transition-normal);
  cursor: pointer;
  position: relative;
  border: 1px solid var(--border-color);
}

.instrument-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-xl);
  border-color: var(--primary-light);
}

.card-cover {
  width: 100%;
  height: 180px;
  overflow: hidden;
  position: relative;
  background: var(--bg-muted);
}

.card-cover img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform var(--transition-slow);
}

.instrument-card:hover .card-cover img {
  transform: scale(1.08);
}

.card-category-dot {
  position: absolute;
  top: 12px;
  left: 12px;
  width: 12px;
  height: 12px;
  border-radius: var(--radius-full);
  box-shadow: 0 0 0 3px rgba(255,255,255,0.5);
}

[data-theme="dark"] .card-category-dot {
  box-shadow: 0 0 0 3px rgba(30,41,59,0.5);
}

.card-category-dot[data-cat="keyboard"] { background: var(--cat-keyboard); }
.card-category-dot[data-cat="string"] { background: var(--cat-string); }
.card-category-dot[data-cat="woodwind"] { background: var(--cat-woodwind); }
.card-category-dot[data-cat="brass"] { background: var(--cat-brass); }
.card-category-dot[data-cat="percussion"] { background: var(--cat-percussion); }
.card-category-dot[data-cat="folk"] { background: var(--cat-folk); }
.card-category-dot[data-cat="electronic"] { background: var(--cat-electronic); }

.card-favorite {
  position: absolute;
  top: 12px;
  right: 12px;
  width: 36px;
  height: 36px;
  border-radius: var(--radius-full);
  background: rgba(255,255,255,0.9);
  backdrop-filter: blur(8px);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 18px;
  transition: all var(--transition-fast);
  border: none;
  cursor: pointer;
  z-index: 2;
}

[data-theme="dark"] .card-favorite {
  background: rgba(30,41,59,0.9);
}

.card-favorite:hover {
  transform: scale(1.15);
}

.card-favorite.active {
  background: var(--danger-color);
  color: white;
}

.card-body {
  padding: 16px;
}

.card-title-row {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 8px;
  margin-bottom: 6px;
}

.card-name {
  font-size: 17px;
  font-weight: 700;
  color: var(--text-primary);
  line-height: 1.3;
}

.card-en-name {
  font-size: 12px;
  color: var(--text-muted);
  margin-bottom: 12px;
  font-style: italic;
}

.card-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 12px;
}

.difficulty-tag {
  padding: 3px 10px;
  border-radius: var(--radius-full);
  font-size: 11px;
  font-weight: 600;
  color: white;
}

.difficulty-tag[data-diff="0"] { background: var(--diff-0); }
.difficulty-tag[data-diff="1"] { background: var(--diff-1); }
.difficulty-tag[data-diff="2"] { background: var(--diff-2); }
.difficulty-tag[data-diff="3"] { background: var(--diff-3); }
.difficulty-tag[data-diff="4"] { background: var(--diff-4); }
.difficulty-tag[data-diff="5"] { background: var(--diff-5); }

.card-stats {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-top: 12px;
  border-top: 1px dashed var(--border-light);
}

.stat-item-mini {
  display: flex;
  align-items: center;
  gap: 4px;
  font-size: 12px;
  color: var(--text-secondary);
}

.stat-item-mini .icon {
  font-size: 13px;
}

.stat-item-mini .value {
  font-weight: 600;
  color: var(--text-primary);
}

.price-tag {
  font-weight: 700;
  font-size: 13px;
  color: var(--warning-color);
}

.card-famous-pieces {
  margin-top: 10px;
  padding-top: 10px;
  border-top: 1px solid var(--border-light);
}

.pieces-title {
  font-size: 11px;
  color: var(--text-muted);
  margin-bottom: 6px;
  font-weight: 500;
}

.pieces-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
}

.piece-tag {
  padding: 3px 8px;
  background: var(--bg-surface-alt);
  border-radius: var(--radius-sm);
  font-size: 11px;
  color: var(--text-secondary);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  max-width: 100%;
}

/* ===== Modal 弹窗 ===== */
.modal {
  position: fixed;
  inset: 0;
  z-index: 1000;
  display: none;
  align-items: center;
  justify-content: center;
  padding: 16px;
}

.modal.active {
  display: flex;
}

.modal-mask {
  position: absolute;
  inset: 0;
  background: rgba(0, 0, 0, 0.6);
  backdrop-filter: blur(4px);
  animation: fadeIn var(--transition-normal);
}

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

.modal-content {
  position: relative;
  background: var(--bg-surface);
  border-radius: var(--radius-xl);
  max-width: 920px;
  width: 100%;
  max-height: 90vh;
  overflow-y: auto;
  box-shadow: var(--shadow-xl);
  animation: modalIn var(--transition-normal);
  scrollbar-width: thin;
  scrollbar-color: var(--bg-muted) transparent;
}

.modal-content::-webkit-scrollbar {
  width: 8px;
}

.modal-content::-webkit-scrollbar-track {
  background: transparent;
}

.modal-content::-webkit-scrollbar-thumb {
  background: var(--bg-muted);
  border-radius: 4px;
}

.modal-small {
  max-width: 520px;
}

@keyframes modalIn {
  from {
    opacity: 0;
    transform: translateY(20px) scale(0.96);
  }
  to {
    opacity: 1;
    transform: translateY(0) scale(1);
  }
}

.modal-close {
  position: absolute;
  top: 16px;
  right: 16px;
  width: 36px;
  height: 36px;
  border-radius: var(--radius-full);
  background: var(--bg-surface-alt);
  color: var(--text-secondary);
  font-size: 24px;
  font-weight: 400;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--transition-fast);
  z-index: 10;
}

.modal-close:hover {
  background: var(--danger-color);
  color: white;
  transform: rotate(90deg);
}

.detail-loading {
  padding: 80px 0;
  display: flex;
  justify-content: center;
}

/* ===== 详情页头部 ===== */
.detail-header {
  display: grid;
  grid-template-columns: 280px 1fr;
  gap: 32px;
  padding: 32px;
  border-bottom: 1px solid var(--border-color);
}

.detail-cover {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.detail-cover > img {
  width: 100%;
  height: 220px;
  object-fit: cover;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
}

.detail-gallery {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 8px;
}

.gallery-thumb {
  width: 100%;
  height: 64px;
  object-fit: cover;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all var(--transition-fast);
  border: 2px solid transparent;
}

.gallery-thumb:hover {
  border-color: var(--primary-color);
  transform: scale(1.05);
}

.detail-info {
  display: flex;
  flex-direction: column;
  min-width: 0;
}

.detail-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 12px;
}

.category-tag {
  padding: 4px 12px;
  border-radius: var(--radius-full);
  font-size: 12px;
  font-weight: 600;
  color: white;
}

.category-tag[data-cat="keyboard"] { background: var(--cat-keyboard); }
.category-tag[data-cat="string"] { background: var(--cat-string); }
.category-tag[data-cat="woodwind"] { background: var(--cat-woodwind); }
.category-tag[data-cat="brass"] { background: var(--cat-brass); }
.category-tag[data-cat="percussion"] { background: var(--cat-percussion); }
.category-tag[data-cat="folk"] { background: var(--cat-folk); }
.category-tag[data-cat="electronic"] { background: var(--cat-electronic); }

.detail-name {
  font-size: 32px;
  font-weight: 800;
  color: var(--text-primary);
  line-height: 1.2;
  margin-bottom: 6px;
}

.detail-en-name {
  font-size: 15px;
  color: var(--text-muted);
  font-style: italic;
  margin-bottom: 20px;
}

.detail-stats {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  margin-bottom: 20px;
}

.detail-stats .stat-item {
  background: var(--bg-surface-alt);
  border-radius: var(--radius-md);
  padding: 12px;
  text-align: center;
  transition: transform var(--transition-fast);
}

.detail-stats .stat-item:hover {
  transform: translateY(-2px);
}

.detail-stats .stat-icon {
  font-size: 20px;
  display: block;
  margin-bottom: 4px;
}

.detail-stats .stat-value {
  font-size: 16px;
  font-weight: 700;
  color: var(--text-primary);
  display: block;
}

.detail-stats .stat-label {
  font-size: 11px;
  color: var(--text-muted);
}

.detail-actions {
  display: flex;
  align-items: center;
  gap: 16px;
  flex-wrap: wrap;
}

.btn-favorite {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 10px 20px;
  border-radius: var(--radius-md);
  background: var(--bg-surface-alt);
  font-size: 14px;
  font-weight: 600;
  transition: all var(--transition-fast);
  border: 2px solid transparent;
}

.btn-favorite:hover {
  border-color: var(--danger-color);
  background: rgba(239,68,68,0.1);
}

.btn-favorite.active {
  background: var(--danger-color);
  color: white;
  border-color: var(--danger-color);
}

.detail-tags-list {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.detail-tags-list .tag-item {
  padding: 4px 10px;
  background: var(--bg-surface-alt);
  border-radius: var(--radius-sm);
  font-size: 12px;
  color: var(--text-secondary);
}

/* ===== 详情 Tab ===== */
.detail-tabs {
  display: flex;
  padding: 0 32px;
  border-bottom: 1px solid var(--border-color);
  overflow-x: auto;
  gap: 2px;
  scrollbar-width: none;
}

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

.detail-tab {
  padding: 16px 16px;
  font-size: 14px;
  font-weight: 600;
  color: var(--text-muted);
  position: relative;
  transition: all var(--transition-fast);
  white-space: nowrap;
  border-bottom: 3px solid transparent;
  margin-bottom: -1px;
}

.detail-tab:hover {
  color: var(--primary-color);
}

.detail-tab.active {
  color: var(--primary-color);
  border-bottom-color: var(--primary-color);
}

.detail-content {
  padding: 24px 32px;
}

.tab-pane {
  display: none;
  animation: fadeIn var(--transition-normal);
}

.tab-pane.active {
  display: block;
}

.section-title {
  font-size: 18px;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 16px;
  padding-bottom: 8px;
  border-bottom: 2px solid var(--bg-surface-alt);
}

.overview-section, .structure-section, .basics-section, .buying-section {
  margin-bottom: 28px;
}

.overview-section p {
  color: var(--text-secondary);
  line-height: 1.8;
  font-size: 14px;
  white-space: pre-line;
}

.characteristics-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 12px;
}

.characteristic-item {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  padding: 14px;
  background: var(--bg-surface-alt);
  border-radius: var(--radius-md);
  transition: all var(--transition-fast);
}

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

.char-icon {
  font-size: 22px;
  flex-shrink: 0;
}

.char-text {
  font-size: 13px;
  color: var(--text-secondary);
  line-height: 1.6;
}

/* ===== 构造介绍 ===== */
.parts-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(160px, 1fr));
  gap: 12px;
}

.part-item {
  padding: 14px;
  background: var(--bg-surface-alt);
  border-radius: var(--radius-md);
  border-left: 4px solid var(--primary-color);
  transition: all var(--transition-fast);
}

.part-item:hover {
  transform: translateX(4px);
  box-shadow: var(--shadow-sm);
}

.part-name {
  font-weight: 700;
  font-size: 14px;
  color: var(--text-primary);
  margin-bottom: 4px;
}

.part-desc {
  font-size: 12px;
  color: var(--text-muted);
  line-height: 1.5;
}

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

.diagram-item {
  display: grid;
  grid-template-columns: 120px 1fr;
  gap: 16px;
  padding: 16px;
  background: var(--bg-surface-alt);
  border-radius: var(--radius-md);
  align-items: center;
}

.diagram-item img {
  width: 100%;
  height: 100px;
  object-fit: cover;
  border-radius: var(--radius-sm);
}

.diagram-content h4 {
  font-size: 15px;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 6px;
}

.diagram-content p {
  font-size: 13px;
  color: var(--text-secondary);
  line-height: 1.7;
}

/* ===== 入门基础 ===== */
.posture-content {
  padding: 20px;
  background: linear-gradient(135deg, rgba(99,102,241,0.05), rgba(236,72,153,0.05));
  border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
}

.posture-content p {
  color: var(--text-secondary);
  line-height: 1.9;
  font-size: 14px;
  white-space: pre-line;
}

.posture-content ul {
  margin-top: 12px;
  padding-left: 20px;
}

.posture-content li {
  margin-bottom: 8px;
  color: var(--text-secondary);
  font-size: 14px;
}

.finger-charts-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 16px;
}

.finger-chart-item {
  padding: 16px;
  background: var(--bg-surface-alt);
  border-radius: var(--radius-md);
  text-align: center;
}

.finger-chart-item img {
  width: 100%;
  height: 140px;
  object-fit: contain;
  margin-bottom: 12px;
  background: white;
  border-radius: var(--radius-sm);
  padding: 8px;
}

[data-theme="dark"] .finger-chart-item img {
  background: var(--bg-surface);
}

.finger-chart-item h4 {
  font-size: 14px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 4px;
}

.finger-chart-item p {
  font-size: 12px;
  color: var(--text-muted);
}

.theory-content {
  padding: 20px;
  background: var(--bg-surface-alt);
  border-radius: var(--radius-md);
}

.theory-content p {
  color: var(--text-secondary);
  line-height: 1.8;
  font-size: 14px;
  white-space: pre-line;
  margin-bottom: 12px;
}

.theory-content h4 {
  font-size: 15px;
  font-weight: 600;
  color: var(--text-primary);
  margin: 16px 0 8px;
}

/* ===== 练习计划表 ===== */
.practice-switch {
  display: flex;
  gap: 8px;
  margin-bottom: 20px;
  background: var(--bg-surface-alt);
  padding: 4px;
  border-radius: var(--radius-lg);
  width: fit-content;
}

.practice-plan-btn {
  padding: 10px 20px;
  border-radius: var(--radius-md);
  font-size: 14px;
  font-weight: 600;
  color: var(--text-secondary);
  transition: all var(--transition-fast);
}

.practice-plan-btn.active {
  background: var(--primary-color);
  color: white;
  box-shadow: 0 2px 8px rgba(99,102,241,0.3);
}

.practice-table {
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  overflow: hidden;
}

.practice-phase {
  margin-bottom: 0;
  border-bottom: 1px solid var(--border-color);
}

.practice-phase:last-child {
  border-bottom: none;
}

.phase-header {
  padding: 14px 20px;
  background: var(--bg-surface-alt);
  font-weight: 700;
  font-size: 15px;
  color: var(--text-primary);
  display: flex;
  align-items: center;
  gap: 10px;
}

.phase-badge {
  padding: 3px 10px;
  border-radius: var(--radius-full);
  font-size: 11px;
  font-weight: 600;
  background: var(--primary-color);
  color: white;
}

.phase-days {
  font-size: 12px;
  color: var(--text-muted);
  font-weight: 400;
}

.practice-days {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 1px;
  background: var(--border-color);
}

.practice-day {
  background: var(--bg-surface);
  padding: 14px;
  transition: background var(--transition-fast);
}

.practice-day:hover {
  background: var(--bg-surface-alt);
}

.day-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 8px;
}

.day-number {
  font-weight: 700;
  font-size: 13px;
  color: var(--primary-color);
}

.day-duration {
  font-size: 11px;
  padding: 2px 8px;
  background: var(--bg-surface-alt);
  border-radius: var(--radius-full);
  color: var(--text-muted);
}

.day-content {
  font-size: 13px;
  color: var(--text-secondary);
  line-height: 1.6;
  white-space: pre-line;
}

/* ===== 入门曲目 ===== */
.pieces-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 16px;
}

.piece-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  overflow: hidden;
  transition: all var(--transition-normal);
}

.piece-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: var(--primary-light);
}

.piece-cover {
  width: 100%;
  height: 120px;
  object-fit: cover;
  background: var(--bg-muted);
}

.piece-body {
  padding: 14px;
}

.piece-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 8px;
  margin-bottom: 8px;
}

.piece-title {
  font-size: 15px;
  font-weight: 700;
  color: var(--text-primary);
  line-height: 1.3;
}

.piece-difficulty {
  flex-shrink: 0;
  padding: 2px 8px;
  border-radius: var(--radius-sm);
  font-size: 10px;
  font-weight: 600;
  color: white;
}

.piece-difficulty[data-diff="1"] { background: var(--diff-1); }
.piece-difficulty[data-diff="2"] { background: var(--diff-2); }
.piece-difficulty[data-diff="3"] { background: var(--diff-3); }
.piece-difficulty[data-diff="4"] { background: var(--diff-4); }
.piece-difficulty[data-diff="5"] { background: var(--diff-5); }

.piece-meta {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-top: 12px;
  padding-top: 10px;
  border-top: 1px dashed var(--border-light);
}

.piece-composer {
  font-size: 12px;
  color: var(--text-muted);
}

.piece-video-btn {
  display: flex;
  align-items: center;
  gap: 4px;
  padding: 6px 12px;
  background: var(--primary-color);
  color: white;
  border-radius: var(--radius-md);
  font-size: 12px;
  font-weight: 600;
  transition: all var(--transition-fast);
  text-decoration: none;
}

.piece-video-btn:hover {
  background: var(--primary-dark);
  transform: scale(1.05);
}

/* ===== 选购指南 ===== */
.brands-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
  gap: 12px;
}

.brand-item {
  padding: 16px;
  background: var(--bg-surface-alt);
  border-radius: var(--radius-md);
  text-align: center;
  transition: all var(--transition-fast);
  border: 2px solid transparent;
}

.brand-item:hover {
  border-color: var(--primary-color);
  transform: translateY(-2px);
}

.brand-tier {
  display: inline-block;
  padding: 2px 8px;
  border-radius: var(--radius-sm);
  font-size: 10px;
  font-weight: 600;
  margin-bottom: 8px;
}

.brand-tier.premium { background: rgba(245,158,11,0.2); color: var(--warning-color); }
.brand-tier.mid { background: rgba(99,102,241,0.2); color: var(--primary-color); }
.brand-tier.entry { background: rgba(16,185,129,0.2); color: var(--success-color); }

.brand-name {
  font-size: 16px;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 4px;
}

.brand-origin {
  font-size: 11px;
  color: var(--text-muted);
  margin-bottom: 8px;
}

.brand-desc {
  font-size: 12px;
  color: var(--text-secondary);
  line-height: 1.5;
}

.price-range-content {
  padding: 20px;
  background: var(--bg-surface-alt);
  border-radius: var(--radius-md);
}

.price-tier {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 12px 0;
  border-bottom: 1px dashed var(--border-color);
}

.price-tier:last-child {
  border-bottom: none;
}

.price-tier-label {
  display: flex;
  align-items: center;
  gap: 10px;
}

.price-tier-dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
}

.price-tier-name {
  font-weight: 600;
  font-size: 14px;
  color: var(--text-primary);
}

.price-tier-range {
  color: var(--warning-color);
  font-weight: 700;
  font-size: 14px;
}

.price-tier-desc {
  font-size: 12px;
  color: var(--text-muted);
  margin-left: 20px;
  flex: 1;
}

.channels-list {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 12px;
}

.channel-item {
  padding: 16px;
  background: var(--bg-surface-alt);
  border-radius: var(--radius-md);
  transition: all var(--transition-fast);
}

.channel-item:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-sm);
}

.channel-icon {
  font-size: 28px;
  margin-bottom: 8px;
}

.channel-name {
  font-weight: 700;
  font-size: 14px;
  color: var(--text-primary);
  margin-bottom: 4px;
}

.channel-tips {
  font-size: 12px;
  color: var(--text-secondary);
  line-height: 1.6;
}

.pitfalls-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.pitfalls-list li {
  padding: 14px 16px 14px 44px;
  background: rgba(239,68,68,0.06);
  border-radius: var(--radius-md);
  border-left: 4px solid var(--danger-color);
  position: relative;
  color: var(--text-secondary);
  font-size: 14px;
  line-height: 1.7;
}

.pitfalls-list li::before {
  content: '⚠️';
  position: absolute;
  left: 14px;
  top: 14px;
  font-size: 18px;
}

/* ===== FAQ ===== */
.faqs-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.faq-item {
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  overflow: hidden;
  transition: all var(--transition-fast);
}

.faq-item:hover {
  box-shadow: var(--shadow-sm);
}

.faq-question {
  padding: 16px 20px;
  font-weight: 600;
  color: var(--text-primary);
  background: var(--bg-surface-alt);
  font-size: 14px;
  display: flex;
  align-items: flex-start;
  gap: 10px;
}

.faq-question::before {
  content: 'Q:';
  color: var(--primary-color);
  font-weight: 800;
  flex-shrink: 0;
}

.faq-answer {
  padding: 14px 20px 14px 46px;
  color: var(--text-secondary);
  font-size: 14px;
  line-height: 1.8;
  white-space: pre-line;
  border-top: 1px solid var(--border-light);
}

/* ===== 详情页底部 ===== */
.detail-footer {
  padding: 24px 32px 32px;
  border-top: 1px solid var(--border-color);
  background: var(--bg-surface-alt);
}

.related-section {
  margin-bottom: 28px;
}

.related-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(160px, 1fr));
  gap: 12px;
}

.related-card {
  background: var(--bg-surface);
  border-radius: var(--radius-md);
  overflow: hidden;
  cursor: pointer;
  transition: all var(--transition-fast);
  border: 1px solid var(--border-color);
}

.related-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
  border-color: var(--primary-light);
}

.related-cover {
  width: 100%;
  height: 100px;
  object-fit: cover;
  background: var(--bg-muted);
}

.related-body {
  padding: 10px 12px;
}

.related-name {
  font-size: 13px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 4px;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.related-meta {
  display: flex;
  justify-content: space-between;
  font-size: 11px;
  color: var(--text-muted);
}

.resources-section .resources-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
}

.resources-section h4 {
  font-size: 15px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 12px;
  padding-left: 8px;
  border-left: 4px solid var(--primary-color);
}

.resource-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.resource-list li {
  padding: 12px 16px;
  background: var(--bg-surface);
  border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
  transition: all var(--transition-fast);
}

.resource-list li:hover {
  border-color: var(--primary-light);
  transform: translateX(4px);
}

.resource-title {
  font-weight: 600;
  font-size: 13px;
  color: var(--text-primary);
  margin-bottom: 4px;
}

.resource-author {
  font-size: 11px;
  color: var(--text-muted);
}

/* ===== 收藏夹弹窗 ===== */
.fav-modal-title {
  padding: 24px 32px;
  font-size: 22px;
  font-weight: 700;
  border-bottom: 1px solid var(--border-color);
}

.fav-list {
  padding: 16px;
  max-height: 60vh;
  overflow-y: auto;
}

.fav-item {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 12px;
  border-radius: var(--radius-md);
  transition: all var(--transition-fast);
  cursor: pointer;
  margin-bottom: 8px;
}

.fav-item:hover {
  background: var(--bg-surface-alt);
}

.fav-item img {
  width: 64px;
  height: 64px;
  object-fit: cover;
  border-radius: var(--radius-md);
  flex-shrink: 0;
}

.fav-item-info {
  flex: 1;
  min-width: 0;
}

.fav-item-name {
  font-weight: 600;
  font-size: 14px;
  color: var(--text-primary);
  margin-bottom: 2px;
}

.fav-item-cat {
  font-size: 12px;
  color: var(--text-muted);
}

.fav-remove {
  width: 32px;
  height: 32px;
  border-radius: var(--radius-full);
  background: var(--bg-surface-alt);
  color: var(--text-muted);
  font-size: 14px;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--transition-fast);
  flex-shrink: 0;
}

.fav-remove:hover {
  background: var(--danger-color);
  color: white;
}

/* ===== 回到顶部 ===== */
.back-to-top {
  position: fixed;
  bottom: 32px;
  right: 32px;
  width: 48px;
  height: 48px;
  border-radius: var(--radius-full);
  background: linear-gradient(135deg, var(--primary-color), var(--primary-dark));
  color: white;
  font-size: 20px;
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: var(--shadow-lg);
  transition: all var(--transition-normal);
  z-index: 99;
}

.back-to-top:hover {
  transform: translateY(-4px);
  box-shadow: 0 12px 24px rgba(99, 102, 241, 0.4);
}

.back-to-top.hidden {
  opacity: 0;
  transform: translateY(20px);
  pointer-events: none;
}

/* ===== 页脚 ===== */
.site-footer {
  background: var(--bg-surface);
  border-top: 1px solid var(--border-color);
  padding: 32px 0;
  text-align: center;
}

.footer-text {
  font-size: 15px;
  color: var(--text-secondary);
  margin-bottom: 8px;
  font-weight: 500;
}

.footer-copyright {
  font-size: 12px;
  color: var(--text-muted);
}

/* ===== 响应式 1200px ===== */
@media (max-width: 1200px) {
  .container {
    max-width: 100%;
  }

  .card-grid {
    grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  }
}

/* ===== 响应式 768px ===== */
@media (max-width: 768px) {
  .container {
    padding: 0 16px;
  }

  .hero-section {
    padding: 32px 0 24px;
  }

  .hero-title {
    font-size: 28px;
  }

  .hero-subtitle {
    font-size: 14px;
    margin-bottom: 24px;
  }

  .search-box {
    padding: 4px 4px 4px 12px;
  }

  #searchInput {
    padding: 10px 6px;
    font-size: 14px;
  }

  .filter-section {
    padding: 16px 0;
  }

  .tab-btn {
    padding: 6px 12px;
    font-size: 12px;
  }

  .filter-footer {
    flex-direction: column;
    align-items: flex-start;
    gap: 12px;
  }

  .main-content {
    padding: 24px 0 48px;
  }

  .card-grid {
    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
    gap: 16px;
  }

  .card-cover {
    height: 150px;
  }

  .detail-header {
    grid-template-columns: 1fr;
    gap: 24px;
    padding: 24px;
  }

  .detail-cover > img {
    height: 240px;
  }

  .detail-name {
    font-size: 26px;
  }

  .detail-stats {
    grid-template-columns: repeat(3, 1fr);
  }

  .detail-tabs {
    padding: 0 16px;
  }

  .detail-tab {
    padding: 14px 12px;
    font-size: 13px;
  }

  .detail-content {
    padding: 20px 16px;
  }

  .detail-footer {
    padding: 20px 16px 24px;
  }

  .resources-section .resources-row {
    grid-template-columns: 1fr;
    gap: 20px;
  }

  .diagram-item {
    grid-template-columns: 1fr;
  }

  .diagram-item img {
    height: 140px;
  }

  .back-to-top {
    bottom: 20px;
    right: 20px;
    width: 44px;
    height: 44px;
  }

  .modal-content {
    border-radius: var(--radius-lg);
  }
}

/* ===== 响应式 480px ===== */
@media (max-width: 480px) {
  :root {
    --header-height: 56px;
  }

  .header-inner {
    padding: 0 12px;
  }

  .logo-text {
    font-size: 17px;
  }

  .logo-icon {
    font-size: 24px;
  }

  .hero-section {
    padding: 24px 0 16px;
  }

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

  .hero-subtitle {
    font-size: 13px;
    margin-bottom: 18px;
  }

  .tab-group {
    gap: 6px;
  }

  .tab-btn {
    padding: 5px 10px;
    font-size: 11px;
  }

  .card-grid {
    grid-template-columns: repeat(auto-fill, minmax(160px, 1fr));
    gap: 12px;
  }

  .card-cover {
    height: 120px;
  }

  .card-body {
    padding: 12px;
  }

  .card-name {
    font-size: 14px;
  }

  .card-en-name {
    font-size: 11px;
  }

  .card-stats {
    flex-wrap: wrap;
    gap: 6px;
  }

  .modal {
    padding: 0;
  }

  .modal-content {
    max-height: 100vh;
    border-radius: 0;
  }

  .modal-close {
    top: 12px;
    right: 12px;
  }

  .detail-header {
    padding: 56px 16px 20px;
    gap: 16px;
  }

  .detail-cover > img {
    height: 180px;
  }

  .detail-name {
    font-size: 22px;
  }

  .detail-stats {
    grid-template-columns: 1fr 1fr 1fr;
    gap: 8px;
  }

  .detail-stats .stat-item {
    padding: 10px 6px;
  }

  .detail-stats .stat-icon {
    font-size: 16px;
  }

  .detail-stats .stat-value {
    font-size: 13px;
  }

  .detail-stats .stat-label {
    font-size: 10px;
  }

  .detail-tabs {
    padding: 0 12px;
  }

  .detail-tab {
    padding: 12px 10px;
    font-size: 12px;
  }

  .detail-content {
    padding: 16px 12px;
  }

  .section-title {
    font-size: 16px;
  }

  .characteristics-grid,
  .parts-grid,
  .finger-charts-grid,
  .pieces-grid,
  .brands-grid,
  .channels-list,
  .related-grid {
    grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
    gap: 10px;
  }

  .practice-days {
    grid-template-columns: 1fr;
  }

  .detail-footer {
    padding: 16px 12px 20px;
  }

  .back-to-top {
    bottom: 16px;
    right: 16px;
    width: 40px;
    height: 40px;
    font-size: 18px;
  }

  .fav-modal-title {
    padding: 56px 20px 20px;
    font-size: 18px;
  }
}