/* ==========================================================================
   UI TOKENS & SHARED SYSTEM
   ========================================================================== */

/* --- Tokens --- */
:root {
  /* Spacing */
  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;

  /* Border Radius */
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 20px;
  --radius-pill: 999px;

  /* Transitions */
  --trans-fast: 0.15s ease;
  --trans-normal: 0.25s ease;
  --trans-slow: 0.5s ease;

  /* Shadows */
  --shadow-sm: 0 2px 8px rgba(0,0,0,0.15);
  --shadow-md: 0 4px 15px rgba(0,0,0,0.2);
  --shadow-lg: 0 8px 30px rgba(0,0,0,0.25);
  
  /* Glass Effects */
  --glass-bg: rgba(255, 255, 255, 0.1);
  --glass-bg-hover: rgba(255, 255, 255, 0.15);
  --glass-border: rgba(255, 255, 255, 0.16);
  --glass-blur: blur(16px);
}

/* ==========================================================================
   SHARED UTILITY CLASSES
   ========================================================================== */

/* --- Glass Panels --- */
.glass-panel {
  background: var(--panel-surface, var(--glass-bg));
  border: 1px solid var(--panel-border, var(--glass-border));
  border-radius: var(--radius-lg);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  box-shadow: var(--shadow-md);
}

/* --- Shared Buttons --- */
.mood-button {
  border: none;
  border-radius: var(--radius-lg);
  background: rgba(15, 20, 40, 0.82);
  border: 1px solid var(--glass-border);
  color: #ffffff;
  cursor: pointer;
  font-weight: 700;
  text-shadow: 0 0 12px rgba(0,0,0,0.35);
  box-shadow: var(--shadow-lg);
  backdrop-filter: var(--glass-blur);
  transition: transform var(--trans-normal), background var(--trans-normal), border-color var(--trans-normal);
  line-height: 1.2;
}

.mood-button:hover {
  transform: translateY(-3px) scale(1.03);
  background: rgba(25, 35, 70, 0.95);
  border-color: rgba(255, 255, 255, 0.24);
}

.icon-button {
  display: flex;
  align-items: center;
  justify-content: center;
  border: none;
  border-radius: var(--radius-lg);
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  color: var(--panel-title, #ffffff);
  cursor: pointer;
  backdrop-filter: var(--glass-blur);
  transition: background var(--trans-fast), transform var(--trans-fast);
}

.icon-button:hover {
  background: var(--glass-bg-hover);
  transform: scale(1.05);
}

/* --- Typography --- */
.section-title {
  font-family: 'Poppins', sans-serif;
  font-weight: 700;
  color: var(--panel-title, #ffffff);
  margin-bottom: var(--space-md);
  letter-spacing: 0.02em;
}

/* --- Cards --- */
.mood-card {
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-md);
  padding: var(--space-md);
  transition: background var(--trans-fast);
}

.mood-card:hover {
  background: var(--glass-bg);
}

/* --- Custom Scrollbar --- */
@media (hover: hover) and (pointer: fine) {
  .custom-scroll::-webkit-scrollbar {
    width: 5px;
    height: 5px;
  }
  .custom-scroll::-webkit-scrollbar-track {
    background: transparent;
  }
  .custom-scroll::-webkit-scrollbar-thumb {
    background: rgba(255, 255, 255, 0.08);
    border-radius: 10px;
  }
  .custom-scroll:hover::-webkit-scrollbar-thumb {
    background: rgba(255, 255, 255, 0.16);
  }
  .custom-scroll::-webkit-scrollbar-thumb:hover {
    background: rgba(255, 255, 255, 0.28);
  }
}

/* ==========================================================================
   LOCAL MUSIC LIBRARY PANEL
   ========================================================================== */

#library-panel {
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.library-toolbar {
  padding: 1rem;
  border-bottom: 1px solid var(--glass-border);
  display: flex;
  flex-direction: column;
  gap: 0.8rem;
  flex-shrink: 0;
}

.library-search-wrap {
  position: relative;
  display: flex;
  align-items: center;
}

#library-search {
  width: 100%;
  background: var(--panel-surface-2);
  border: 1px solid var(--panel-border);
  border-radius: 12px;
  padding: 0.8rem 1rem;
  color: var(--panel-text);
  font-family: inherit;
  font-size: 0.95rem;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  line-height: 1.5;
}

#library-search::placeholder {
  color: var(--panel-placeholder);
  opacity: 0.7;
}

#library-search:focus {
  outline: none;
  border-color: var(--mood-accent);
  background: rgba(0, 0, 0, 0.4);
  box-shadow: 0 0 15px var(--mood-glow);
}

.library-filter {
  display: flex;
  gap: 0.4rem;
  overflow-x: auto;
  padding-bottom: 0.2rem;
}

.library-filter::-webkit-scrollbar {
  display: none;
}

.library-filter-btn {
  /* Default to neutral/all */
  --mood-rgb: 229, 231, 235;
  --mood-hex: #e5e7eb;

  background: rgba(var(--mood-rgb), 0.08);
  border: 1px solid rgba(var(--mood-rgb), 0.15);
  color: rgba(var(--mood-rgb), 0.85);
  padding: 0.35rem 0.9rem;
  border-radius: 20px;
  font-size: 0.85rem;
  font-weight: 500;
  cursor: pointer;
  white-space: nowrap;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.library-filter-btn:hover {
  background: rgba(var(--mood-rgb), 0.15);
  border-color: rgba(var(--mood-rgb), 0.3);
  color: #fff;
  box-shadow: 0 0 8px rgba(var(--mood-rgb), 0.2);
}

.library-filter-btn.active {
  background: rgba(var(--mood-rgb), 0.25);
  border-color: var(--mood-hex);
  color: #fff;
  box-shadow: 0 0 15px rgba(var(--mood-rgb), 0.4);
}

/* Chill */
.library-filter-btn[data-filter="chill"] {
  --mood-rgb: 165, 180, 252;
  --mood-hex: #a5b4fc;
}

/* Happy */
.library-filter-btn[data-filter="happy"] {
  --mood-rgb: 253, 224, 71;
  --mood-hex: #fde047;
}

/* Sad */
.library-filter-btn[data-filter="sad"] {
  --mood-rgb: 147, 197, 253;
  --mood-hex: #93c5fd;
}

/* Sleep */
.library-filter-btn[data-filter="sleep"] {
  --mood-rgb: 216, 180, 254;
  --mood-hex: #d8b4fe;
}

/* All / Others */
.library-filter-btn[data-filter="all"],
.library-filter-btn[data-filter="others"] {
  --mood-rgb: 229, 231, 235;
  --mood-hex: #e5e7eb;
}

.library-list {
  flex: 1;
  overflow-y: auto;
  padding: 0.5rem;
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.library-track-item {
  display: flex;
  align-items: center;
  padding: 0.6rem;
  border-radius: 8px;
  cursor: pointer;
  transition: background 0.2s;
  position: relative;
}

.library-track-item:hover {
  background: rgba(255, 255, 255, 0.08);
}

.library-track-item.active {
  background: rgba(255, 255, 255, 0.12);
}

.library-track-item.active::before {
  content: '';
  position: absolute;
  left: 0;
  top: 50%;
  transform: translateY(-50%);
  height: 60%;
  width: 3px;
  background: #4ade80;
  border-radius: 0 4px 4px 0;
}

.library-track-thumb {
  width: 40px;
  height: 40px;
  border-radius: 6px;
  background: rgba(0, 0, 0, 0.3);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-right: 0.8rem;
  flex-shrink: 0;
  font-size: 1.2rem;
}

.library-track-info {
  flex: 1;
  min-width: 0;
}

.library-track-title {
  font-weight: 600;
  font-size: 0.95rem;
  color: #fff;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  margin-bottom: 0.1rem;
}

.library-track-artist {
  font-size: 0.8rem;
  color: rgba(255, 255, 255, 0.6);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.library-track-mood {
  font-size: 0.7rem;
  padding: 0.1rem 0.4rem;
  background: rgba(255, 255, 255, 0.1);
  border-radius: 4px;
  color: rgba(255, 255, 255, 0.8);
  margin-left: 0.5rem;
  text-transform: capitalize;
}

.library-empty {
  padding: 2rem;
  text-align: center;
  color: rgba(255, 255, 255, 0.5);
  font-size: 0.9rem;
}