/* === CSS Variables === */
:root {
  --bg-primary: #f8f9fc;
  --bg-card: #ffffff;
  --bg-header: #ffffff;
  --bg-modal: #ffffff;
  --bg-input: #f0f2f5;
  --text-primary: #1a1a2e;
  --text-secondary: #6b7280;
  --text-muted: #9ca3af;
  --accent: #ff6b9d;
  --accent-hover: #e55585;
  --accent-glow: rgba(255, 107, 157, 0.3);
  --border: #e5e7eb;
  --shadow: rgba(0, 0, 0, 0.08);
  --shadow-lg: rgba(0, 0, 0, 0.12);
  --lv-easy: #4caf50;
  --lv-basic: #2196f3;
  --lv-advanced: #ff9800;
  --lv-expert: #f44336;
  --lv-master: #9c27b0;
  --lv-remaster: #e91e63;
  --lv-utage: #ff5722;
  --radius: 12px;
  --radius-sm: 8px;
  --transition: 0.2s ease;
}

[data-theme="dark"] {
  --bg-primary: #0f0f1a;
  --bg-card: #1a1a30;
  --bg-header: #161628;
  --bg-modal: #1e1e36;
  --bg-input: #252545;
  --text-primary: #e8e8f0;
  --text-secondary: #a0a0b8;
  --text-muted: #6b6b80;
  --accent: #ff6b9d;
  --accent-hover: #ff8bb5;
  --accent-glow: rgba(255, 107, 157, 0.4);
  --border: #2a2a45;
  --shadow: rgba(0, 0, 0, 0.3);
  --shadow-lg: rgba(0, 0, 0, 0.5);
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Noto Sans SC', sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  min-height: 100vh;
  transition: background var(--transition), color var(--transition);
  position: relative;
}

body::before {
  content: '';
  position: fixed;
  inset: 0;
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
  background-attachment: fixed;
  opacity: 0;
  z-index: 0;
  pointer-events: none;
  transition: opacity var(--transition);
}

/* === Header === */
header {
  background: var(--bg-header);
  border-bottom: 1px solid var(--border);
  padding: 16px 24px;
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: 0 2px 8px var(--shadow);
  transition: background var(--transition), border-color var(--transition);
  position: relative;
}

.header-content {
  display: flex;
  align-items: center;
  gap: 16px;
  max-width: 1400px;
  margin: 0 auto;
  flex-wrap: wrap;
}

.logo {
  font-size: 20px;
  font-weight: 700;
  color: var(--accent);
  white-space: nowrap;
  letter-spacing: 1px;
}

.search-bar {
  display: flex;
  gap: 8px;
  flex: 1;
  min-width: 200px;
}

.search-bar input {
  flex: 1;
  padding: 10px 16px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--bg-input);
  color: var(--text-primary);
  font-size: 14px;
  outline: none;
  transition: border-color var(--transition), background var(--transition);
}

.search-bar input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-glow);
}

.search-bar select {
  padding: 10px 12px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--bg-input);
  color: var(--text-primary);
  font-size: 14px;
  outline: none;
  cursor: pointer;
  transition: border-color var(--transition), background var(--transition);
}

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

.song-count {
  font-size: 13px;
  color: var(--text-muted);
  white-space: nowrap;
}

.theme-toggle {
  width: 40px;
  height: 40px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--bg-input);
  color: var(--text-primary);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--transition);
}

.theme-toggle:hover {
  border-color: var(--accent);
  color: var(--accent);
}

/* Show sun in dark mode, moon in light mode */
.icon-sun { display: none; }
.icon-moon { display: block; }
[data-theme="dark"] .icon-sun { display: block; }
[data-theme="dark"] .icon-moon { display: none; }

/* === Song Grid === */
main {
  max-width: 1400px;
  margin: 0 auto;
  padding: 24px;
}

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

.loading {
  text-align: center;
  padding: 40px;
  color: var(--text-muted);
  font-size: 16px;
}

/* === Song Card === */
.song-card {
  background: var(--bg-card);
  border-radius: var(--radius);
  border: 1px solid var(--border);
  overflow: hidden;
  cursor: pointer;
  transition: transform 0.15s ease, box-shadow var(--transition), border-color var(--transition), background var(--transition);
}

.song-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 8px 24px var(--shadow-lg);
  border-color: var(--accent);
}

.song-card-thumb {
  width: 100%;
  aspect-ratio: 1;
  object-fit: cover;
  background: var(--bg-input);
}

.song-card-body {
  padding: 12px;
}

.song-card-title {
  font-size: 14px;
  font-weight: 600;
  line-height: 1.3;
  margin-bottom: 4px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.song-card-artist {
  font-size: 12px;
  color: var(--text-secondary);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  margin-bottom: 8px;
}

.song-card-levels {
  display: flex;
  gap: 4px;
  flex-wrap: wrap;
}

.level-badge {
  font-size: 11px;
  padding: 2px 6px;
  border-radius: 4px;
  font-weight: 600;
  color: #fff;
  line-height: 1.4;
}

.level-badge.lv-1 { background: var(--lv-easy); }
.level-badge.lv-2 { background: var(--lv-basic); }
.level-badge.lv-3 { background: var(--lv-advanced); }
.level-badge.lv-4 { background: var(--lv-expert); }
.level-badge.lv-5 { background: var(--lv-master); }
.level-badge.lv-6 { background: var(--lv-remaster); }
.level-badge.lv-7 { background: var(--lv-utage); }

/* === Pagination === */
.pagination {
  display: flex;
  justify-content: center;
  gap: 8px;
  padding: 24px 0;
}

.pagination button {
  padding: 8px 16px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--bg-card);
  color: var(--text-primary);
  cursor: pointer;
  transition: all var(--transition);
  font-size: 14px;
}

.pagination button:hover {
  border-color: var(--accent);
  color: var(--accent);
}

.pagination button.active {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
}

.pagination button:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

/* === Modal === */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.6);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 200;
  padding: 24px;
  animation: fadeIn 0.2s ease;
}

.modal-overlay[hidden] { display: none; }

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

.modal-content {
  background: var(--bg-modal);
  border-radius: 16px;
  max-width: 640px;
  width: 100%;
  max-height: 90vh;
  overflow-y: auto;
  box-shadow: 0 20px 60px var(--shadow-lg);
  animation: slideUp 0.25s ease;
  transition: background var(--transition);
}

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

.modal-close {
  position: absolute;
  top: 12px;
  right: 16px;
  background: none;
  border: none;
  font-size: 24px;
  color: var(--text-secondary);
  cursor: pointer;
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 8px;
  transition: background var(--transition);
}

.modal-close:hover { background: var(--bg-input); }

.modal-body {
  display: flex;
  gap: 24px;
  padding: 24px;
}

.modal-thumb {
  width: 200px;
  flex-shrink: 0;
}

.modal-thumb img {
  width: 200px;
  height: 200px;
  object-fit: cover;
  border-radius: var(--radius);
}

.modal-info {
  flex: 1;
}

.modal-info h2 {
  font-size: 20px;
  margin-bottom: 16px;
  line-height: 1.3;
}

.info-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 8px;
  margin-bottom: 16px;
}

.info-item {
  display: flex;
  gap: 8px;
}

.info-label {
  font-size: 12px;
  color: var(--text-muted);
  min-width: 60px;
}

.info-value {
  font-size: 14px;
  color: var(--text-primary);
}

.difficulty-section h3 {
  font-size: 14px;
  color: var(--text-secondary);
  margin-bottom: 8px;
}

.level-badges {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
  margin-bottom: 16px;
}

.level-badge-large {
  font-size: 13px;
  padding: 4px 10px;
  border-radius: 6px;
  font-weight: 600;
  color: #fff;
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

.level-badge-large.lv-1 { background: var(--lv-easy); }
.level-badge-large.lv-2 { background: var(--lv-basic); }
.level-badge-large.lv-3 { background: var(--lv-advanced); }
.level-badge-large.lv-4 { background: var(--lv-expert); }
.level-badge-large.lv-5 { background: var(--lv-master); }
.level-badge-large.lv-6 { background: var(--lv-remaster); }
.level-badge-large.lv-7 { background: var(--lv-utage); }

.level-badge-large .lv-name {
  font-size: 11px;
  opacity: 0.85;
}

.download-btn {
  width: 100%;
  padding: 12px;
  background: var(--accent);
  color: #fff;
  border: none;
  border-radius: var(--radius);
  font-size: 16px;
  font-weight: 600;
  cursor: pointer;
  transition: background var(--transition);
}

.download-btn:hover { background: var(--accent-hover); }

/* === Captcha Modal === */
.captcha-content {
  background: var(--bg-modal);
  border-radius: 16px;
  padding: 32px;
  max-width: 320px;
  width: 100%;
  text-align: center;
  box-shadow: 0 20px 60px var(--shadow-lg);
  animation: slideUp 0.25s ease;
  transition: background var(--transition);
}

.captcha-content h3 {
  font-size: 16px;
  margin-bottom: 16px;
}

.captcha-svg {
  margin: 16px auto;
  display: flex;
  justify-content: center;
}

.captcha-svg svg {
  border-radius: 6px;
}

.captcha-input-row {
  display: flex;
  gap: 8px;
  margin-top: 12px;
}

.captcha-input-row input {
  flex: 1;
  padding: 10px 12px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--bg-input);
  color: var(--text-primary);
  font-size: 16px;
  text-align: center;
  letter-spacing: 4px;
  outline: none;
  transition: border-color var(--transition), background var(--transition);
}

.captcha-input-row input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-glow);
}

.captcha-submit {
  padding: 10px 20px;
  background: var(--accent);
  color: #fff;
  border: none;
  border-radius: var(--radius-sm);
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  transition: background var(--transition);
}

.captcha-submit:hover { background: var(--accent-hover); }

.captcha-error {
  color: #f44336;
  font-size: 13px;
  margin-top: 8px;
}

.captcha-refresh {
  margin-top: 12px;
  padding: 6px 12px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--bg-input);
  color: var(--text-secondary);
  font-size: 13px;
  cursor: pointer;
  transition: all var(--transition);
}

.captcha-refresh:hover {
  border-color: var(--accent);
  color: var(--accent);
}

/* === Responsive === */
@media (max-width: 768px) {
  .header-content { flex-wrap: wrap; }
  .search-bar { order: 3; width: 100%; }
  .search-bar select { display: none; }
  .song-grid { grid-template-columns: repeat(2, 1fr); gap: 12px; }
  .modal-body { flex-direction: column; }
  .modal-thumb { width: 100%; }
  .modal-thumb img { width: 100%; height: auto; aspect-ratio: 1; }
  .info-grid { grid-template-columns: 1fr; }
  main { padding: 16px; }
  header { padding: 12px 16px; }
}

@media (max-width: 480px) {
  .song-grid { grid-template-columns: repeat(2, 1fr); gap: 8px; }
  .song-card-body { padding: 8px; }
  .song-card-title { font-size: 13px; }
}

@media (min-width: 1400px) {
  .song-grid { grid-template-columns: repeat(5, 1fr); }
}