:root {
  --bg-main: #090d16;
  --bg-card: #111827;
  --bg-card-subtle: #1e293b;
  --bg-card-hover: #26354a;
  --border-subtle: rgba(255, 255, 255, 0.08);
  --border-accent: rgba(6, 182, 212, 0.35);

  --text-primary: #f8fafc;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;

  --accent-cyan: #06b6d4;
  --accent-cyan-glow: rgba(6, 182, 212, 0.25);
  --accent-emerald: #10b981;
  --accent-rose: #f43f5e;
  --accent-amber: #f59e0b;

  --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
  --radius-lg: 16px;
  --radius-md: 10px;
  --radius-sm: 6px;
}

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

body {
  background-color: var(--bg-main);
  color: var(--text-primary);
  font-family: var(--font-sans);
  min-height: 100vh;
  display: flex;
  justify-content: center;
  align-items: flex-start;
  padding: 24px 16px;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

.app-container {
  width: 100%;
  max-width: 860px;
  display: flex;
  flex-direction: column;
  gap: 20px;
}

/* Header */
.app-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-bottom: 8px;
}

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

.logo-pulse {
  width: 14px;
  height: 14px;
  border-radius: 50%;
  background: var(--accent-cyan);
  box-shadow: 0 0 14px var(--accent-cyan);
  animation: pulse-dot 2s infinite ease-in-out;
}

@keyframes pulse-dot {
  0%, 100% { transform: scale(1); opacity: 0.9; }
  50% { transform: scale(1.25); opacity: 0.5; }
}

.brand h1 {
  font-size: 1.4rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  background: linear-gradient(135deg, #ffffff 40%, var(--accent-cyan) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

/* Toggle Switch */
.toggle-control {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  cursor: pointer;
  user-select: none;
  font-size: 0.85rem;
  color: var(--text-secondary);
}

.toggle-control input {
  display: none;
}

.toggle-slider {
  width: 36px;
  height: 20px;
  background-color: var(--bg-card-subtle);
  border-radius: 20px;
  position: relative;
  transition: background-color 0.2s ease;
  border: 1px solid var(--border-subtle);
}

.toggle-slider::after {
  content: '';
  position: absolute;
  top: 2px;
  left: 2px;
  width: 14px;
  height: 14px;
  background-color: #fff;
  border-radius: 50%;
  transition: transform 0.2s ease;
}

.toggle-control input:checked + .toggle-slider {
  background-color: var(--accent-cyan);
  border-color: var(--accent-cyan);
}

.toggle-control input:checked + .toggle-slider::after {
  transform: translateX(16px);
}

/* Tab Navigation */
.tabs-nav {
  display: flex;
  gap: 8px;
  background: var(--bg-card);
  padding: 6px;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-subtle);
}

.tab-btn {
  flex: 1;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 10px 16px;
  background: transparent;
  color: var(--text-secondary);
  border: none;
  border-radius: var(--radius-sm);
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s ease;
}

.tab-btn:hover {
  color: var(--text-primary);
  background: rgba(255, 255, 255, 0.04);
}

.tab-btn.active {
  background: var(--bg-card-subtle);
  color: var(--accent-cyan);
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.4);
}

/* Panels */
.tab-panel {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.tab-panel[hidden] {
  display: none;
}

/* Hero Display Card */
.main-display-card {
  background: linear-gradient(180deg, var(--bg-card) 0%, rgba(17, 24, 39, 0.8) 100%);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 24px 28px;
  display: flex;
  flex-direction: column;
  align-items: center;
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.35);
  position: relative;
  overflow: hidden;
}

.display-top {
  width: 100%;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.status-badge {
  font-size: 0.8rem;
  font-weight: 600;
  padding: 4px 10px;
  border-radius: 20px;
  background: var(--bg-card-subtle);
  color: var(--text-secondary);
  border: 1px solid var(--border-subtle);
}

.status-badge.active-state {
  color: var(--accent-cyan);
  border-color: var(--accent-cyan-glow);
  background: rgba(6, 182, 212, 0.1);
}

.btn-reset {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 5px 12px;
  background: transparent;
  color: var(--text-muted);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
  font-size: 0.8rem;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.15s ease;
}

.btn-reset:hover {
  color: var(--accent-rose);
  border-color: rgba(244, 63, 94, 0.3);
  background: rgba(244, 63, 94, 0.08);
}

.bpm-hero {
  margin: 18px 0;
  display: flex;
  align-items: baseline;
  justify-content: center;
  gap: 8px;
}

.bpm-value-wrapper {
  display: inline-flex;
  align-items: baseline;
}

.bpm-integer {
  font-size: 5rem;
  font-weight: 800;
  line-height: 1;
  letter-spacing: -0.04em;
  color: var(--text-primary);
  font-variant-numeric: tabular-nums;
}

.bpm-decimal {
  font-size: 2.2rem;
  font-weight: 700;
  color: var(--accent-cyan);
  margin-left: 2px;
  font-variant-numeric: tabular-nums;
}

.bpm-unit {
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--accent-cyan);
  letter-spacing: 0.05em;
}

.hero-submetrics {
  width: 100%;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  border-top: 1px solid var(--border-subtle);
  padding-top: 18px;
  margin-top: 6px;
}

.submetric {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
}

.submetric-label {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
  margin-bottom: 4px;
}

.submetric-val {
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--text-primary);
}

.rating-pill {
  color: var(--accent-emerald);
}

/* Tap Interactive Button */
.tap-interactive-section {
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 10px 0;
}

.tap-button {
  width: 190px;
  height: 190px;
  border-radius: 50%;
  background: radial-gradient(circle at 40% 30%, #1e293b, #0f172a);
  border: 3px solid var(--accent-cyan);
  box-shadow: 0 0 25px var(--accent-cyan-glow), inset 0 2px 10px rgba(255, 255, 255, 0.1);
  color: #fff;
  cursor: pointer;
  position: relative;
  outline: none;
  touch-action: manipulation;
  user-select: none;
  -webkit-tap-highlight-color: transparent;
  transition: transform 0.08s ease, box-shadow 0.08s ease;
}

.tap-button:active, .tap-button.active-pulse {
  transform: scale(0.94);
  box-shadow: 0 0 40px var(--accent-cyan), inset 0 0 15px rgba(6, 182, 212, 0.5);
}

.tap-inner {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
}

.tap-title {
  font-size: 2.2rem;
  font-weight: 800;
  letter-spacing: 0.08em;
}

.tap-counter {
  font-size: 0.85rem;
  color: var(--accent-cyan);
  margin-top: 4px;
  font-weight: 500;
}

.tap-hint {
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-top: 14px;
}

kbd {
  background: var(--bg-card-subtle);
  border: 1px solid var(--border-subtle);
  padding: 2px 6px;
  border-radius: 4px;
  font-size: 0.8rem;
  color: var(--text-secondary);
}

/* Audio Tab Styles */
.audio-input-section {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.audio-config-row {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
}

.config-label {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-secondary);
}

.duration-selector {
  display: inline-flex;
  background: var(--bg-card);
  padding: 3px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-subtle);
  gap: 4px;
}

.duration-btn {
  background: transparent;
  color: var(--text-muted);
  border: none;
  padding: 6px 14px;
  border-radius: 4px;
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.15s ease;
}

.duration-btn:hover {
  color: var(--text-primary);
}

.duration-btn.active {
  background: var(--bg-card-subtle);
  color: var(--accent-cyan);
  box-shadow: 0 1px 4px rgba(0, 0, 0, 0.3);
}

.audio-actions-row {
  display: flex;
  align-items: center;
  gap: 14px;
  flex-wrap: wrap;
}

.btn-primary {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  background: var(--accent-cyan);
  color: #05131e;
  border: none;
  border-radius: var(--radius-md);
  padding: 12px 22px;
  font-size: 0.95rem;
  font-weight: 700;
  cursor: pointer;
  transition: all 0.2s ease;
}

.btn-primary:hover {
  background: #22d3ee;
  box-shadow: 0 0 20px var(--accent-cyan-glow);
}

.rec-dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--accent-rose);
}

.btn-primary.recording {
  background: var(--accent-rose);
  color: #fff;
}

.btn-primary.recording .rec-dot {
  background: #fff;
  animation: blink 0.7s infinite alternate;
}

@keyframes blink {
  from { opacity: 1; }
  to { opacity: 0.2; }
}

.btn-secondary {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: var(--bg-card);
  color: var(--text-primary);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 11px 20px;
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s ease;
}

.btn-secondary:hover {
  background: var(--bg-card-subtle);
  border-color: rgba(255, 255, 255, 0.2);
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  border: 0;
}

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

/* Drop Zone */
.drop-zone {
  border: 2px dashed var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 28px;
  text-align: center;
  background: rgba(17, 24, 39, 0.4);
  cursor: pointer;
  transition: all 0.2s ease;
}

.drop-zone.drag-over {
  border-color: var(--accent-cyan);
  background: rgba(6, 182, 212, 0.08);
}

.drop-content {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  color: var(--text-secondary);
}

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

.drop-subtext {
  font-size: 0.75rem;
  color: var(--text-muted);
}

.audio-progress-bar-wrap[hidden],
.audio-results-section[hidden] {
  display: none !important;
}

/* Progress bar */
.audio-progress-bar-wrap {
  display: flex;
  flex-direction: column;
  gap: 8px;
  background: var(--bg-card);
  padding: 14px 18px;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-subtle);
}

.progress-info {
  display: flex;
  justify-content: space-between;
  font-size: 0.85rem;
  font-weight: 600;
}

.progress-bar {
  width: 100%;
  height: 6px;
  background: var(--bg-card-subtle);
  border-radius: 4px;
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  width: 0%;
  background: var(--accent-cyan);
  transition: width 0.1s linear;
}

/* Audio Results */
.audio-results-section {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.audio-bpm-card {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 22px;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.audio-bpm-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 14px;
}

.label-subtle {
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-muted);
  font-weight: 600;
}

.audio-hero {
  margin: 4px 0 0 0;
}

.audio-stats {
  display: flex;
  gap: 10px;
}

.stat-pill {
  background: var(--bg-card-subtle);
  border: 1px solid var(--border-subtle);
  padding: 6px 12px;
  border-radius: var(--radius-sm);
  font-size: 0.85rem;
}

.stat-name {
  color: var(--text-muted);
  margin-right: 4px;
}

.stat-val {
  color: var(--accent-cyan);
  font-weight: 700;
}

.harmonics-row {
  display: flex;
  align-items: center;
  gap: 10px;
  padding-top: 12px;
  border-top: 1px solid var(--border-subtle);
  flex-wrap: wrap;
}

.harmonics-title {
  font-size: 0.8rem;
  color: var(--text-muted);
}

.btn-chip {
  background: var(--bg-card-subtle);
  border: 1px solid var(--border-subtle);
  color: var(--text-secondary);
  padding: 4px 10px;
  border-radius: 20px;
  font-size: 0.8rem;
  cursor: pointer;
  transition: all 0.15s ease;
}

.btn-chip:hover {
  background: var(--bg-card-hover);
  color: var(--text-primary);
  border-color: rgba(255, 255, 255, 0.2);
}

/* Visualizer Card */
.visualizer-card {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 20px;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.vis-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 10px;
}

.vis-title-group h3 {
  font-size: 1rem;
  font-weight: 700;
}

.vis-hint {
  font-size: 0.75rem;
  color: var(--accent-emerald);
}

.canvas-container {
  width: 100%;
  height: 150px;
  background: #060911;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-subtle);
  position: relative;
  overflow: hidden;
  cursor: pointer;
}

#waveformCanvas {
  width: 100%;
  height: 100%;
  display: block;
}

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

.btn-play {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: var(--bg-card-subtle);
  color: var(--text-primary);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
  padding: 8px 16px;
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.15s ease;
}

.btn-play:hover {
  background: var(--accent-cyan);
  color: #05131e;
  border-color: var(--accent-cyan);
}

.btn-icon {
  background: var(--bg-card-subtle);
  color: var(--text-muted);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
  padding: 8px 10px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
}

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

.playback-time {
  font-size: 0.85rem;
  color: var(--text-muted);
  font-variant-numeric: tabular-nums;
  margin-left: auto;
}

/* Footer */
.app-footer {
  text-align: center;
  padding: 16px 0;
  font-size: 0.75rem;
  color: var(--text-muted);
}

/* Responsive Breakpoints */
@media (max-width: 640px) {
  body {
    padding: 14px 10px;
  }
  .bpm-integer {
    font-size: 4rem;
  }
  .bpm-decimal {
    font-size: 1.8rem;
  }
  .tap-button {
    width: 160px;
    height: 160px;
  }
  .hero-submetrics {
    grid-template-columns: 1fr;
    gap: 8px;
  }
}

/* Local file identity */
.track-info[hidden], .track-info [hidden] { display: none !important; }
.track-info { display: flex; align-items: center; gap: 20px; padding: 20px; border: 1px solid var(--border-subtle); border-radius: var(--radius-lg); background: var(--bg-card); }
.track-artwork { width: 112px; height: 112px; flex-shrink: 0; border-radius: 12px; overflow: hidden; background: linear-gradient(140deg, #164e63, #1e293b); display: grid; place-items: center; }
.track-artwork img { width: 100%; height: 100%; object-fit: cover; }
.artwork-placeholder { font-size: 3rem; color: var(--accent-cyan); }
.track-copy { min-width: 0; color: var(--text-secondary); font-size: 0.8rem; overflow-wrap: anywhere; }
.track-copy h2 { color: var(--text-primary); font-size: 1.2rem; line-height: 1.25; margin: 4px 0; }
.track-artist { color: var(--accent-cyan); font-weight: 600; font-size: 1rem; }
.track-filename { margin-top: 8px; color: var(--text-secondary); }

/* Fixed-size canvas with native touch scrolling; track is only a spacer. */
.canvas-container { height: 176px; overflow-x: auto; overflow-y: hidden; scrollbar-color: #475569 #060911; touch-action: pan-x pan-y; }
#waveformTrack { height: 160px; position: relative; }
#waveformCanvas { position: sticky; left: 0; height: 160px; }
.waveform-tools { display: flex; align-items: center; justify-content: space-between; flex-wrap: wrap; gap: 10px; font-size: 0.8rem; color: var(--text-secondary); }
.waveform-tools label { display: flex; align-items: center; gap: 8px; min-height: 36px; }
.waveform-tools select { background: var(--bg-card-subtle); color: var(--text-primary); border: 1px solid var(--border-subtle); padding: 7px; border-radius: 6px; font-size: 16px; }
.waveform-tools input, .waveform-navigation input { accent-color: var(--accent-cyan); }
.waveform-caption { display: flex; justify-content: space-between; flex-wrap: wrap; gap: 6px; font-size: 0.75rem; color: var(--text-secondary); font-variant-numeric: tabular-nums; }
#waveformPosition { width: 100%; min-height: 32px; }
.playback-controls { flex-wrap: wrap; }
.audio-stats { flex-wrap: wrap; }
.canvas-container:focus-visible { outline: 2px solid var(--accent-cyan); outline-offset: 2px; }
@media (max-width: 480px) {
  .track-info { gap: 12px; padding: 14px; align-items: flex-start; }
  .track-artwork { width: 76px; height: 76px; }
  .track-copy h2 { font-size: 1.05rem; }
  .visualizer-card { padding: 14px; }
  .audio-bpm-header { flex-wrap: wrap; }
  .playback-time { font-size: 0.8rem; }
}

/* Tap convergence and streamlined audio input */
.audio-input-controls { display: flex; gap: 20px; align-items: flex-start; }
.record-control { display: flex; flex-direction: column; align-items: stretch; gap: 10px; }
.record-control .record-btn { justify-content: center; min-height: 48px; }
.record-control .duration-selector { justify-content: center; }
.record-control .duration-btn { flex: 1; min-height: 36px; }
.file-upload-label { justify-content: center; min-height: 48px; }
.mobile-only { display: none; }
.tap-trim-control { display: flex; flex-direction: column; align-items: center; gap: 5px; }
.tap-trim-control p { font-size: 0.75rem; color: var(--text-secondary); }
.tap-trim-control .toggle-control { min-height: 36px; color: var(--text-primary); }
.tap-trim-control input { display: block; position: absolute; width: 1px; height: 1px; opacity: 0; }
.tap-trim-control input:focus-visible + .toggle-slider { outline: 2px solid white; outline-offset: 3px; }
.convergence-card { background: var(--bg-card); border: 1px solid var(--border-subtle); border-radius: var(--radius-lg); padding: 16px; }
.convergence-header { display: flex; flex-wrap: wrap; gap: 8px; align-items: center; justify-content: space-between; }
.convergence-header h2 { font-size: 0.95rem; }
.stability-badge { border-radius: 20px; padding: 4px 9px; background: var(--bg-card-subtle); color: var(--text-secondary); font-size: 0.75rem; font-weight: 600; }
.stability-badge[data-state="settling"] { color: #fbbf24; background: #302716; }
.stability-badge[data-state="stable"] { color: #34d399; background: #12302b; }
#tapStabilityDetail { min-height: 2.5em; font-size: 0.8rem; color: var(--text-secondary); margin-top: 8px; }
#tapConvergenceChart { display: block; width: 100%; height: auto; max-height: 210px; }
.convergence-stats { display: flex; flex-wrap: wrap; gap: 6px 16px; justify-content: space-between; font-size: 0.75rem; color: var(--text-secondary); font-variant-numeric: tabular-nums; }
button:disabled { opacity: 0.5; cursor: default; }
@media (max-width: 640px), (hover: none) and (pointer: coarse) {
  .desktop-only { display: none !important; }
  .mobile-only { display: inline; }
  .audio-input-controls { flex-direction: column; align-items: stretch; gap: 20px; }
  .record-control { width: 100%; }
  .record-control .duration-selector { align-self: center; min-width: 200px; }
  .hero-submetrics { grid-template-columns: repeat(3,minmax(0,1fr)); gap: 8px; padding-top: 10px; }
  .submetric-label { font-size: 0.6rem; }
  .submetric-val { font-size: 0.8rem; }
  #tabTap { gap: 10px; }
  #tabTap .main-display-card { padding: 14px; }
  #tabTap .bpm-hero { margin: 10px 0; }
  #tabTap .tap-button { width: 132px; height: 132px; }
  #tabTap .tap-interactive-section { padding: 0; }
  #tabTap .tap-hint { margin-top: 6px; font-size: 0.75rem; }
  .convergence-card { padding: 12px; }
  #tapStabilityDetail { min-height: 0; font-size: 0.75rem; }
}