/* ===== CSS Custom Properties ===== */
:root {
  --bg-primary: #0f0f0f;
  --bg-secondary: #1a1a2e;
  --bg-card: #16213e;
  --bg-input: #1a1a2e;
  --text-primary: #e0e0e0;
  --text-secondary: #a0a0b0;
  --text-muted: #666680;
  --accent: #7c5bf5;
  --accent-hover: #9b7fff;
  --accent-subtle: rgba(124, 91, 245, 0.15);
  --border: #2a2a40;
  --chip-bg: #1e1e36;
  --chip-active: #7c5bf5;
  --chip-text: #c0c0d0;
  --chip-active-text: #ffffff;
  --star: #f5c542;
  --shadow: 0 2px 12px rgba(0, 0, 0, 0.3);
  --radius: 8px;
  --radius-lg: 12px;
}

body.light-theme {
  --bg-primary: #f5f5f7;
  --bg-secondary: #ffffff;
  --bg-card: #ffffff;
  --bg-input: #f0f0f5;
  --text-primary: #1a1a2e;
  --text-secondary: #555566;
  --text-muted: #999aaa;
  --accent: #6c3ce0;
  --accent-hover: #8b5cf6;
  --accent-subtle: rgba(108, 60, 224, 0.1);
  --border: #e0e0ea;
  --chip-bg: #ededf5;
  --chip-active: #6c3ce0;
  --chip-text: #555566;
  --chip-active-text: #ffffff;
  --star: #e6a817;
  --shadow: 0 2px 12px rgba(0, 0, 0, 0.08);
}

/* ===== Reset ===== */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Hiragino Sans",
    "Hiragino Kaku Gothic ProN", "Noto Sans JP", "Meiryo", sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  transition: background 0.3s, color 0.3s;
  min-height: 100vh;
}

/* ===== App Container ===== */
.app {
  max-width: 900px;
  margin: 0 auto;
  padding: 20px 16px 60px;
}

/* ===== Header ===== */
.header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 16px 0 12px;
  border-bottom: 1px solid var(--border);
  margin-bottom: 20px;
}

.header__title {
  font-size: 1.5rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.header__actions {
  display: flex;
  gap: 8px;
  align-items: center;
}

.lang-toggle {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 6px 14px;
  cursor: pointer;
  font-size: 0.82rem;
  font-weight: 600;
  transition: background 0.2s, border-color 0.2s;
  color: var(--text-secondary);
}

.lang-toggle:hover {
  background: var(--accent-subtle);
  border-color: var(--accent);
  color: var(--accent);
}

.theme-toggle {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: 50%;
  width: 40px;
  height: 40px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.2rem;
  transition: background 0.2s, border-color 0.2s;
  color: var(--text-primary);
}

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

/* ===== Search Bar ===== */
.search-bar {
  position: relative;
  margin-bottom: 16px;
}

.search-bar__input {
  width: 100%;
  padding: 14px 48px 14px 18px;
  background: var(--bg-input);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  color: var(--text-primary);
  font-size: 1rem;
  outline: none;
  transition: border-color 0.2s, box-shadow 0.2s;
}

.search-bar__input::placeholder {
  color: var(--text-muted);
}

.search-bar__input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-subtle);
}

.search-bar__icon {
  position: absolute;
  right: 16px;
  top: 50%;
  transform: translateY(-50%);
  font-size: 1.1rem;
  pointer-events: none;
}

/* ===== Filters ===== */
.filters {
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 16px;
  margin-bottom: 16px;
  transition: background 0.3s;
}

.filters__header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 12px;
}

.filters__title {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-secondary);
}

.filters__reset {
  background: none;
  border: none;
  color: var(--accent);
  cursor: pointer;
  font-size: 0.85rem;
  padding: 4px 8px;
  border-radius: var(--radius);
  transition: background 0.2s;
}

.filters__reset:hover {
  background: var(--accent-subtle);
}

.filter-group {
  margin-bottom: 12px;
}

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

.filter-group__label {
  font-size: 0.8rem;
  font-weight: 500;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 8px;
}

.filter-chips {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.chip {
  padding: 6px 14px;
  border-radius: 20px;
  background: var(--chip-bg);
  color: var(--chip-text);
  border: 1px solid var(--border);
  cursor: pointer;
  font-size: 0.85rem;
  transition: all 0.2s;
  user-select: none;
}

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

.chip.active {
  background: var(--chip-active);
  color: var(--chip-active-text);
  border-color: var(--chip-active);
}

.chip .chip__count {
  font-size: 0.75rem;
  opacity: 0.7;
  margin-left: 4px;
}

/* Select */
.filter-select {
  width: 100%;
  padding: 10px 14px;
  background: var(--bg-input);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text-primary);
  font-size: 0.9rem;
  outline: none;
  cursor: pointer;
  transition: border-color 0.2s;
}

.filter-select:focus {
  border-color: var(--accent);
}

/* Checkbox */
.filter-checkbox {
  display: flex;
  align-items: center;
  gap: 8px;
  cursor: pointer;
  font-size: 0.9rem;
  color: var(--text-secondary);
}

.filter-checkbox input[type="checkbox"] {
  width: 18px;
  height: 18px;
  accent-color: var(--accent);
  cursor: pointer;
}

/* ===== Toolbar ===== */
.toolbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 12px;
  padding: 0 4px;
}

.stats {
  font-size: 0.9rem;
  color: var(--text-secondary);
}

.stats span {
  font-weight: 700;
  color: var(--accent);
  font-size: 1.1rem;
}

.sort-controls {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.85rem;
  color: var(--text-secondary);
}

.sort-controls select {
  padding: 6px 10px;
  background: var(--bg-input);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  color: var(--text-primary);
  font-size: 0.85rem;
  outline: none;
  cursor: pointer;
}

/* ===== Song List ===== */
.song-list {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.song-card {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 14px 16px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  transition: border-color 0.2s, box-shadow 0.2s, transform 0.15s;
}

.song-card:hover {
  border-color: var(--accent);
  box-shadow: var(--shadow);
  transform: translateY(-1px);
}

.song-card__star {
  font-size: 1.1rem;
  flex-shrink: 0;
  width: 24px;
  text-align: center;
}

.song-card__star.recommended {
  color: var(--star);
}

.song-card__star.empty {
  color: transparent;
}

.song-card__info {
  flex: 1;
  min-width: 0;
}

.song-card__title {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-primary);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.song-card__artist {
  font-size: 0.82rem;
  color: var(--text-secondary);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  cursor: pointer;
  transition: color 0.2s;
}

.song-card__artist:hover {
  color: var(--accent);
}

.song-card__meta {
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
  flex-shrink: 0;
}

.song-card__tag {
  padding: 2px 8px;
  border-radius: 10px;
  font-size: 0.7rem;
  background: var(--accent-subtle);
  color: var(--accent);
  white-space: nowrap;
}

.song-card__lang {
  padding: 2px 8px;
  border-radius: 10px;
  font-size: 0.7rem;
  background: var(--chip-bg);
  color: var(--text-muted);
  white-space: nowrap;
}

/* Highlight matched text */
.highlight {
  background: var(--star);
  color: #000;
  border-radius: 2px;
  padding: 0 1px;
}

/* ===== Empty State ===== */
.empty-state {
  text-align: center;
  padding: 60px 20px;
  color: var(--text-muted);
}

.empty-state p:first-child {
  font-size: 1.1rem;
  margin-bottom: 8px;
}

.empty-state__hint {
  font-size: 0.85rem;
}

/* ===== Responsive ===== */
@media (max-width: 600px) {
  .app {
    padding: 12px 12px 40px;
  }

  .header__title {
    font-size: 1.2rem;
  }

  .search-bar__input {
    padding: 12px 44px 12px 14px;
    font-size: 0.95rem;
  }

  .song-card {
    padding: 12px;
    gap: 10px;
  }

  .song-card__meta {
    display: none;
  }

  .filters {
    padding: 12px;
  }

  .chip {
    padding: 5px 10px;
    font-size: 0.8rem;
  }
}

/* ===== Animations ===== */
@keyframes fadeIn {
  from { opacity: 0; transform: translateY(8px); }
  to   { opacity: 1; transform: translateY(0); }
}

.song-card {
  animation: fadeIn 0.2s ease-out both;
}

.song-card:nth-child(n+11) {
  animation-delay: 0s;
}