/* ==================== VARIABLES ==================== */
:root {
  --primary: #39d353;
  --primary-dark: #2ea043;
  --primary-light: rgba(57, 211, 83, 0.1);
  --accent: #8b5cf6;
  --accent-light: rgba(139, 92, 246, 0.1);
  --bg-primary: #0d1117;
  --bg-secondary: #161b22;
  --bg-card: #1c2128;
  --bg-input: #0d1117;
  --text-primary: #e6edf3;
  --text-secondary: #8b949e;
  --text-muted: #6e7681;
  --border-color: #30363d;
  --border-light: rgba(255, 255, 255, 0.05);
  --danger: #ef4444;
  --warning: #f59e0b;
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.12);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.15);
  --shadow-lg: 0 8px 30px rgba(0, 0, 0, 0.2);
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-xl: 20px;
  --space-xs: 4px;
  --space-sm: 8px;
  --space-md: 16px;
  --space-lg: 24px;
  --space-xl: 32px;
  --transition: 0.2s ease;
}

[data-theme="light"] {
  --bg-primary: #ffffff;
  --bg-secondary: #f6f8fa;
  --bg-card: #ffffff;
  --bg-input: #f6f8fa;
  --text-primary: #1f2328;
  --text-secondary: #656d76;
  --text-muted: #8b949e;
  --border-color: #d0d7de;
  --border-light: rgba(0, 0, 0, 0.04);
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.06);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.08);
  --shadow-lg: 0 8px 30px rgba(0, 0, 0, 0.1);
}

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

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--space-lg);
}

.text-gradient {
  background: linear-gradient(135deg, var(--primary), #00d2ff);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

/* ==================== HEADER ==================== */
.app-header {
  background: var(--bg-secondary);
  border-bottom: 1px solid var(--border-color);
  padding: var(--space-md) 0;
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(12px);
}

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

.logo {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  text-decoration: none;
  color: var(--text-primary);
  font-size: 1.25rem;
  font-weight: 700;
}

.logo i {
  font-size: 1.5rem;
  color: var(--primary);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: var(--space-md);
}

.icon-btn {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
  background: var(--bg-card);
  color: var(--text-secondary);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--transition);
}

.icon-btn:hover { border-color: var(--primary); color: var(--primary); }

.back-btn {
  padding: 8px 16px;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
  background: var(--bg-card);
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.875rem;
  display: flex;
  align-items: center;
  gap: 6px;
  transition: all var(--transition);
}

.back-btn:hover { border-color: var(--primary); color: var(--primary); }

/* ==================== HERO ==================== */
.hero-section {
  text-align: center;
  padding: var(--space-xl) 0;
}

.hero-icon {
  width: 72px;
  height: 72px;
  border-radius: var(--radius-lg);
  background: var(--primary-light);
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto var(--space-lg);
  animation: heroFloat 3s ease-in-out infinite;
}

@keyframes heroFloat {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-6px); }
}

.hero-icon i {
  font-size: 2rem;
  color: var(--primary);
}

.hero-section h1 {
  font-size: 2.5rem;
  font-weight: 800;
  letter-spacing: -0.03em;
  margin-bottom: var(--space-sm);
}

.hero-section p {
  color: var(--text-secondary);
  max-width: 600px;
  margin: 0 auto;
  font-size: 1rem;
}

/* ==================== UPLOAD AREA ==================== */
.upload-area {
  border: 2px dashed var(--border-color);
  border-radius: var(--radius-xl);
  padding: 60px 40px;
  text-align: center;
  cursor: pointer;
  transition: all var(--transition);
  background: var(--bg-secondary);
  max-width: 700px;
  margin: 0 auto var(--space-xl);
}

.upload-area:hover, .upload-area.dragover {
  border-color: var(--primary);
  background: var(--primary-light);
}

.upload-icon {
  width: 80px;
  height: 80px;
  border-radius: 50%;
  background: var(--primary-light);
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto var(--space-lg);
}

.upload-icon i {
  font-size: 2.5rem;
  color: var(--primary);
}

.upload-area h3 {
  font-size: 1.25rem;
  margin-bottom: var(--space-sm);
}

.upload-area p {
  color: var(--text-secondary);
  margin-bottom: var(--space-lg);
  font-size: 0.875rem;
}

.upload-btn {
  padding: 12px 28px;
  border-radius: var(--radius-md);
  border: none;
  background: var(--primary);
  color: white;
  font-size: 0.9375rem;
  font-weight: 600;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  transition: all var(--transition);
}

.upload-btn:hover {
  background: var(--primary-dark);
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(57, 211, 83, 0.3);
}

/* ==================== WORKSPACE ==================== */
.workspace {
  display: grid;
  grid-template-columns: 1fr 380px;
  gap: var(--space-lg);
  align-items: start;
  margin-bottom: var(--space-xl);
}

/* ==================== TRACKS SECTION ==================== */
.tracks-section {
  background: var(--bg-card);
  border-radius: var(--radius-lg);
  border: 1px solid var(--border-color);
  overflow: hidden;
}

.section-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-md) var(--space-lg);
  border-bottom: 1px solid var(--border-color);
}

.section-header h3 {
  font-size: 0.9375rem;
  display: flex;
  align-items: center;
  gap: 8px;
}

.section-actions {
  display: flex;
  gap: 6px;
}

.btn-sm {
  padding: 6px 12px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-color);
  background: var(--bg-primary);
  color: var(--text-secondary);
  font-size: 0.75rem;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 4px;
  transition: all var(--transition);
}

.btn-sm:hover { border-color: var(--primary); color: var(--primary); }
.btn-sm.danger:hover { border-color: var(--danger); color: var(--danger); }

.track-list {
  padding: var(--space-md);
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
  max-height: 600px;
  overflow-y: auto;
}

.track-list-hint {
  padding: var(--space-sm) var(--space-lg);
  font-size: 0.7rem;
  color: var(--text-muted);
  border-top: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  gap: 4px;
}

/* Track Item */
.track-item {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  padding: var(--space-md);
  border-radius: var(--radius-md);
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  transition: all var(--transition);
  cursor: grab;
  user-select: none;
}

.track-item:active { cursor: grabbing; }
.track-item:hover { border-color: var(--primary); }
.track-item.dragging { opacity: 0.5; border-color: var(--primary); background: var(--primary-light); }
.track-item.drag-over { border-color: var(--primary); box-shadow: 0 0 0 2px var(--primary-light); }

.track-drag {
  color: var(--text-muted);
  font-size: 1.1rem;
  flex-shrink: 0;
  cursor: grab;
}

.track-number {
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background: var(--primary-light);
  color: var(--primary);
  font-size: 0.75rem;
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.track-waveform {
  width: 80px;
  height: 40px;
  flex-shrink: 0;
  border-radius: var(--radius-sm);
  overflow: hidden;
  background: var(--bg-primary);
}

.track-waveform canvas {
  width: 100%;
  height: 100%;
  display: block;
}

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

.track-name {
  font-weight: 600;
  font-size: 0.875rem;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.track-meta {
  font-size: 0.7rem;
  color: var(--text-secondary);
  display: flex;
  gap: 10px;
  margin-top: 2px;
}

/* Track Controls */
.track-controls {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-shrink: 0;
}

.track-volume {
  display: flex;
  align-items: center;
  gap: 4px;
}

.track-volume i {
  font-size: 0.85rem;
  color: var(--text-muted);
}

.track-volume input[type="range"] {
  width: 60px;
  height: 4px;
}

.track-volume-val {
  font-size: 0.65rem;
  color: var(--text-muted);
  min-width: 28px;
  text-align: right;
}

.track-btn {
  width: 28px;
  height: 28px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-color);
  background: var(--bg-primary);
  color: var(--text-secondary);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.75rem;
  transition: all var(--transition);
}

.track-btn:hover { border-color: var(--primary); color: var(--primary); }
.track-btn.danger:hover { border-color: var(--danger); color: var(--danger); }
.track-btn.playing { background: var(--primary); color: white; border-color: var(--primary); }

/* Trim Modal */
.trim-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.6);
  z-index: 500;
  display: flex;
  align-items: center;
  justify-content: center;
  backdrop-filter: blur(4px);
}

.trim-modal {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  width: 500px;
  max-width: 95vw;
  box-shadow: var(--shadow-lg);
}

.trim-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-md) var(--space-lg);
  border-bottom: 1px solid var(--border-color);
}

.trim-header h3 {
  font-size: 1rem;
  display: flex;
  align-items: center;
  gap: 8px;
}

.trim-close {
  width: 32px;
  height: 32px;
  border-radius: var(--radius-sm);
  border: none;
  background: transparent;
  color: var(--text-secondary);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--transition);
}

.trim-close:hover { background: var(--bg-secondary); color: var(--danger); }

.trim-body {
  padding: var(--space-lg);
}

.trim-waveform {
  height: 80px;
  background: var(--bg-secondary);
  border-radius: var(--radius-md);
  margin-bottom: var(--space-md);
  overflow: hidden;
  position: relative;
}

.trim-waveform canvas {
  width: 100%;
  height: 100%;
  display: block;
}

.trim-range-display {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  margin-bottom: var(--space-md);
}

.trim-input-group {
  flex: 1;
}

.trim-input-group label {
  display: block;
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-bottom: 4px;
}

.trim-input {
  width: 100%;
  padding: 8px 12px;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
  background: var(--bg-input);
  color: var(--text-primary);
  font-size: 0.875rem;
  outline: none;
  text-align: center;
  font-family: 'Inter', monospace;
}

.trim-input:focus { border-color: var(--primary); }

.trim-sep {
  color: var(--text-muted);
  font-size: 1.2rem;
  padding-top: 18px;
}

.trim-footer {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: var(--space-sm);
  padding: var(--space-md) var(--space-lg);
  border-top: 1px solid var(--border-color);
}

.trim-btn {
  padding: 8px 20px;
  border-radius: var(--radius-md);
  border: none;
  font-size: 0.875rem;
  font-weight: 600;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 6px;
  transition: all var(--transition);
}

.trim-btn.primary {
  background: var(--primary);
  color: white;
}

.trim-btn.primary:hover { background: var(--primary-dark); }

.trim-btn.secondary {
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
}

.trim-btn.secondary:hover { border-color: var(--primary); }

/* ==================== SETTINGS PANEL ==================== */
.settings-panel {
  display: flex;
  flex-direction: column;
  gap: var(--space-lg);
}

.settings-card, .timeline-card, .player-card {
  background: var(--bg-card);
  border-radius: var(--radius-lg);
  border: 1px solid var(--border-color);
  padding: var(--space-lg);
}

.settings-card h3, .timeline-card h3, .player-card h3 {
  font-size: 0.9375rem;
  margin-bottom: var(--space-lg);
  display: flex;
  align-items: center;
  gap: 8px;
}

.setting-group {
  margin-bottom: var(--space-lg);
}

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

.setting-group > label {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--text-secondary);
  margin-bottom: var(--space-sm);
}

.format-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 8px;
}

.format-btn {
  padding: 10px 8px;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
  background: var(--bg-primary);
  cursor: pointer;
  text-align: center;
  transition: all var(--transition);
}

.format-btn:hover { border-color: var(--primary); }
.format-btn.active { border-color: var(--primary); background: var(--primary-light); }

.format-ext {
  display: block;
  font-weight: 700;
  font-size: 0.875rem;
  color: var(--text-primary);
}

.format-desc {
  display: block;
  font-size: 0.65rem;
  color: var(--text-secondary);
  margin-top: 2px;
}

.format-btn.active .format-ext { color: var(--primary); }

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

.quality-btn {
  padding: 10px 8px;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
  background: var(--bg-primary);
  cursor: pointer;
  text-align: center;
  transition: all var(--transition);
  color: var(--text-primary);
  font-size: 0.8125rem;
}

.quality-btn small { display: block; font-size: 0.65rem; color: var(--text-secondary); margin-top: 2px; }
.quality-btn:hover { border-color: var(--primary); }
.quality-btn.active { border-color: var(--primary); background: var(--primary-light); color: var(--primary); }

.crossfade-control {
  display: flex;
  align-items: center;
  gap: var(--space-md);
}

.crossfade-control input[type="range"] { flex: 1; }

.crossfade-value {
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--primary);
  min-width: 30px;
  text-align: right;
}

.crossfade-hint {
  font-size: 0.7rem;
  color: var(--text-muted);
  margin-top: 4px;
}

.select-input {
  width: 100%;
  padding: 10px 12px;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
  background: var(--bg-input);
  color: var(--text-primary);
  font-size: 0.875rem;
  outline: none;
  cursor: pointer;
}

.select-input:focus { border-color: var(--primary); }

/* ==================== TIMELINE ==================== */
.timeline-visual {
  background: var(--bg-secondary);
  border-radius: var(--radius-md);
  min-height: 60px;
  padding: var(--space-md);
  display: flex;
  align-items: center;
  gap: 4px;
  overflow-x: auto;
}

.timeline-empty {
  width: 100%;
  text-align: center;
  color: var(--text-muted);
  font-size: 0.8125rem;
}

.timeline-block {
  height: 36px;
  min-width: 40px;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.6rem;
  font-weight: 700;
  color: white;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  padding: 0 8px;
  flex-shrink: 0;
  position: relative;
}

.timeline-crossfade {
  width: 16px;
  height: 36px;
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: center;
}

.timeline-crossfade i {
  font-size: 0.7rem;
  color: var(--text-muted);
}

.timeline-info {
  display: flex;
  justify-content: space-between;
  margin-top: var(--space-sm);
  font-size: 0.75rem;
  color: var(--text-secondary);
}

.timeline-info span {
  display: flex;
  align-items: center;
  gap: 4px;
}

/* ==================== PLAYER ==================== */
.audio-player audio {
  border-radius: var(--radius-md);
}

/* ==================== JOIN BUTTON ==================== */
.join-btn {
  width: 100%;
  padding: 14px;
  border-radius: var(--radius-md);
  border: none;
  background: linear-gradient(135deg, var(--primary), #00d2ff);
  color: white;
  font-size: 1rem;
  font-weight: 700;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  transition: all var(--transition);
}

.join-btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 30px rgba(57, 211, 83, 0.3);
}

.join-btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  transform: none;
}

.join-btn i {
  font-size: 1.2rem;
}

/* ==================== PROGRESS ==================== */
.progress-section {
  text-align: center;
}

.progress-bar {
  height: 8px;
  background: var(--bg-secondary);
  border-radius: 4px;
  overflow: hidden;
  margin-bottom: var(--space-sm);
}

.progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--primary), #00d2ff);
  border-radius: 4px;
  width: 0%;
  transition: width 0.3s ease;
}

.progress-text {
  font-size: 0.8125rem;
  color: var(--text-secondary);
}

/* ==================== RESULT ==================== */
.result-section {
  animation: slideUp 0.4s ease;
}

@keyframes slideUp {
  from { opacity: 0; transform: translateY(12px); }
  to { opacity: 1; transform: translateY(0); }
}

.result-card {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  padding: var(--space-md) var(--space-lg);
  background: var(--bg-card);
  border: 1px solid var(--primary);
  border-radius: var(--radius-lg);
  box-shadow: 0 0 0 3px var(--primary-light);
}

.result-card > i {
  font-size: 1.5rem;
  color: var(--primary);
  flex-shrink: 0;
}

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

.result-info strong {
  display: block;
  font-size: 0.875rem;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.result-info span {
  font-size: 0.75rem;
  color: var(--text-secondary);
}

.result-download {
  padding: 8px 16px;
  border-radius: var(--radius-md);
  border: none;
  background: var(--primary);
  color: white;
  font-size: 0.8125rem;
  font-weight: 600;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 6px;
  transition: all var(--transition);
  white-space: nowrap;
}

.result-download:hover { background: var(--primary-dark); }

/* ==================== FEATURES ==================== */
.features-section {
  padding: var(--space-xl) 0 60px;
  text-align: center;
}

.features-section h2 {
  font-size: 1.75rem;
  font-weight: 800;
  margin-bottom: var(--space-xl);
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-lg);
  text-align: left;
}

.feature-card {
  padding: var(--space-lg);
  border-radius: var(--radius-lg);
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  transition: all var(--transition);
}

.feature-card:hover {
  transform: translateY(-4px);
  border-color: var(--primary);
  box-shadow: 0 8px 30px rgba(57, 211, 83, 0.08);
}

.feature-icon {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-md);
  background: var(--primary-light);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: var(--space-md);
}

.feature-icon i { font-size: 1.25rem; color: var(--primary); }
.feature-card h3 { font-size: 1rem; margin-bottom: var(--space-xs); }
.feature-card p { font-size: 0.8125rem; color: var(--text-secondary); line-height: 1.5; }

/* ==================== FOOTER ==================== */
.app-footer {
  padding: var(--space-lg) 0;
  text-align: center;
  border-top: 1px solid var(--border-color);
  font-size: 0.8125rem;
  color: var(--text-secondary);
}

/* ==================== RANGE INPUT ==================== */
input[type="range"] {
  -webkit-appearance: none;
  appearance: none;
  height: 4px;
  border-radius: 2px;
  background: var(--border-color);
  outline: none;
}

input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 14px;
  height: 14px;
  border-radius: 50%;
  background: var(--primary);
  cursor: pointer;
  border: 2px solid white;
  box-shadow: 0 1px 4px rgba(0,0,0,0.2);
}

input[type="range"]::-moz-range-thumb {
  width: 14px;
  height: 14px;
  border-radius: 50%;
  background: var(--primary);
  cursor: pointer;
  border: 2px solid white;
}

/* ==================== TOAST ==================== */
@keyframes slideIn {
  from { transform: translateX(100%); opacity: 0; }
  to { transform: translateX(0); opacity: 1; }
}

/* ==================== RESPONSIVE ==================== */
@media (max-width: 900px) {
  .workspace {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 768px) {
  .hero-section h1 { font-size: 1.75rem; }
  .features-grid { grid-template-columns: 1fr; }
  .format-grid { grid-template-columns: repeat(2, 1fr); }
  .quality-options { grid-template-columns: repeat(3, 1fr); }
  .upload-area { padding: 40px 20px; }
  .track-item { flex-wrap: wrap; }
  .track-waveform { display: none; }
  .track-controls { width: 100%; justify-content: flex-end; }
}

@media (max-width: 480px) {
  .track-volume { display: none; }
  .section-actions { flex-wrap: wrap; }
}