:root {
  --bg: #15171c;
  --panel: #1f232b;
  --text: #e8eaed;
  --muted: #9aa0ab;
  --accent: #5fd0a0;
  --flat: #5b9bd5;
  --sharp: #e0735c;
  --amber: #f5b942;
  --in-tune: #5fd0a0;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  background: radial-gradient(circle at 50% 0%, #232733, var(--bg) 60%);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  padding: 24px;
}

.hidden { display: none !important; }

h1 {
  margin: 0 0 8px;
  font-size: 1.6rem;
  letter-spacing: 0.03em;
  font-weight: 600;
  text-align: center;
}

h2 {
  font-size: 0.95rem;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin: 28px 0 12px;
}

/* ---- Landing screen ---- */

.landing {
  width: min(560px, 92vw);
  text-align: center;
}

.subtitle {
  margin: 0 0 32px;
  color: var(--muted);
  font-size: 0.95rem;
}

.instrument-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: 16px;
}

.instrument-card {
  appearance: none;
  border: 1px solid rgba(255, 255, 255, 0.08);
  border-radius: 20px;
  background: var(--panel);
  color: var(--text);
  padding: 36px 16px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
  cursor: pointer;
  transition: transform 0.12s ease, box-shadow 0.12s ease, border-color 0.12s ease;
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.35);
}
.instrument-card:hover {
  transform: translateY(-2px);
  border-color: var(--accent);
  box-shadow: 0 20px 60px rgba(95, 208, 160, 0.2);
}
.instrument-card:active { transform: translateY(0); }

.instrument-icon { font-size: 2.6rem; }
/* No dedicated bass guitar, viola, or cello emoji exists, so each reuses a
   sibling instrument's emoji with a shifted color to stay distinguishable. */
.instrument-icon.icon-bass { filter: hue-rotate(155deg) saturate(1.15); }
.instrument-icon.icon-viola { filter: hue-rotate(200deg) saturate(1.2); }
.instrument-icon.icon-cello { filter: hue-rotate(100deg) saturate(1.2); }
.instrument-name { font-size: 1.05rem; font-weight: 600; }

/* ---- Tuner screen ---- */

.tuner {
  width: min(480px, 92vw);
  background: var(--panel);
  border-radius: 20px;
  padding: 32px;
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.45);
  text-align: center;
}

.back-btn {
  appearance: none;
  border: none;
  background: none;
  color: var(--muted);
  font-size: 0.85rem;
  cursor: pointer;
  padding: 0;
  margin-bottom: 16px;
}
.back-btn:hover { color: var(--text); }

.controls {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 16px;
  margin: 20px 0 0;
  flex-wrap: wrap;
}

.start-btn {
  appearance: none;
  border: none;
  border-radius: 999px;
  padding: 14px 32px;
  font-size: 1rem;
  font-weight: 600;
  background: var(--accent);
  color: #0d2018;
  cursor: pointer;
  transition: transform 0.12s ease, box-shadow 0.12s ease;
}
.start-btn:hover { transform: translateY(-1px); box-shadow: 0 6px 18px rgba(95, 208, 160, 0.35); }
.start-btn:active { transform: translateY(0); }
.start-btn.listening {
  background: transparent;
  border: 2px solid var(--sharp);
  color: var(--sharp);
}

.reference-pitch {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 0.85rem;
  color: var(--muted);
  white-space: nowrap;
}
.reference-pitch input {
  width: 60px;
  padding: 8px;
  border-radius: 8px;
  border: 1px solid rgba(255, 255, 255, 0.12);
  background: rgba(255, 255, 255, 0.05);
  color: var(--text);
  font-size: 14px;
  text-align: center;
}

.a4-presets {
  display: inline-flex;
  gap: 4px;
}
.a4-preset-btn {
  appearance: none;
  border: 1px solid rgba(255, 255, 255, 0.12);
  border-radius: 6px;
  min-width: 34px;
  min-height: 32px;
  padding: 5px 7px;
  font-size: 0.72rem;
  font-weight: 500;
  background: rgba(255, 255, 255, 0.03);
  color: var(--muted);
  cursor: pointer;
  transition: color 0.12s ease, border-color 0.12s ease, background 0.12s ease;
}
.a4-preset-btn:hover { color: var(--text); border-color: rgba(255, 255, 255, 0.25); }
.a4-preset-btn.active {
  color: #0d2018;
  background: var(--accent);
  border-color: var(--accent);
  font-weight: 700;
}

.capo-control {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 0.85rem;
  color: var(--muted);
  white-space: nowrap;
}
.capo-control select {
  padding: 8px;
  border-radius: 8px;
  border: 1px solid rgba(255, 255, 255, 0.12);
  background: rgba(255, 255, 255, 0.05);
  color: var(--text);
  font-size: 13px;
  cursor: pointer;
}
.capo-control select:focus { outline: none; border-color: var(--accent); }

.stretch-control {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 0.85rem;
  color: var(--muted);
  white-space: nowrap;
  cursor: help;
}
.stretch-control input[type="checkbox"] {
  width: 16px;
  height: 16px;
  accent-color: var(--accent);
  cursor: pointer;
}

.auto-advance-control {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 0.85rem;
  color: var(--muted);
  white-space: nowrap;
  cursor: help;
}
.auto-advance-control input[type="checkbox"] {
  width: 16px;
  height: 16px;
  accent-color: var(--accent);
  cursor: pointer;
}

.cue-control {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 0.85rem;
  color: var(--muted);
  white-space: nowrap;
  cursor: help;
}
.cue-control input[type="checkbox"] {
  width: 16px;
  height: 16px;
  accent-color: var(--accent);
  cursor: pointer;
}

.strobe-control {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 0.85rem;
  color: var(--muted);
  white-space: nowrap;
  cursor: help;
}
.strobe-control input[type="checkbox"] {
  width: 16px;
  height: 16px;
  accent-color: var(--accent);
  cursor: pointer;
}

.spectrum-control {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 0.85rem;
  color: var(--muted);
  white-space: nowrap;
  cursor: help;
}
.spectrum-control input[type="checkbox"] {
  width: 16px;
  height: 16px;
  accent-color: var(--accent);
  cursor: pointer;
}

.strobe-canvas {
  display: block;
  width: 100%;
  max-width: 380px;
  height: 64px;
  margin: 0 auto;
  border-radius: 12px;
  border: 1px solid rgba(255, 255, 255, 0.06);
  background: rgba(0, 0, 0, 0.2);
}

.share-btn {
  appearance: none;
  border: 1px solid rgba(255, 255, 255, 0.12);
  border-radius: 999px;
  padding: 8px 16px;
  font-size: 0.85rem;
  font-weight: 500;
  background: rgba(255, 255, 255, 0.05);
  color: var(--muted);
  cursor: pointer;
  white-space: nowrap;
  transition: color 0.12s ease, border-color 0.12s ease;
}
.share-btn:hover { color: var(--text); border-color: rgba(255, 255, 255, 0.25); }
.share-btn.copied { color: var(--accent); border-color: var(--accent); }

.status {
  color: var(--muted);
  font-size: 0.9rem;
  min-height: 1.2em;
  margin: 14px 0 0;
}

.display { margin-top: 28px; }

.note-row {
  display: flex;
  align-items: baseline;
  justify-content: center;
  gap: 6px;
  margin-bottom: 18px;
}
.note-name {
  font-size: 5rem;
  font-weight: 700;
  line-height: 1;
  letter-spacing: -2px;
  font-variant-ligatures: none;
  transition: color 0.15s ease;
}
.octave {
  font-size: 1.6rem;
  color: var(--muted);
  font-weight: 500;
}

.string-label {
  text-align: center;
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--accent);
  letter-spacing: 0.02em;
  margin: -10px 0 18px;
}
.string-label.no-match {
  color: var(--muted);
  font-weight: 500;
  font-style: italic;
}

.piano-keyboard {
  margin: 0 auto 22px;
  max-width: 320px;
}
.keyboard-octave-label {
  text-align: center;
  font-size: 0.78rem;
  color: var(--muted);
  letter-spacing: 0.06em;
  text-transform: uppercase;
  margin-bottom: 8px;
}
.keyboard-keys {
  position: relative;
  height: 96px;
  display: flex;
  border-radius: 6px;
  overflow: hidden;
  box-shadow: 0 6px 16px rgba(0, 0, 0, 0.3);
}
.white-key {
  flex: 1;
  background: #eceff1;
  border-right: 1px solid rgba(0, 0, 0, 0.25);
  transition: background 0.15s ease;
}
.white-key:last-child { border-right: none; }
.white-key.active { background: var(--accent); }
.black-key {
  position: absolute;
  top: 0;
  width: 8.6%;
  height: 58%;
  background: #1c1e24;
  border-radius: 0 0 3px 3px;
  z-index: 2;
  transition: background 0.15s ease;
}
.black-key.active { background: var(--accent); }

.meter {
  margin: 0 auto;
  max-width: 380px;
}
.meter-scale {
  display: flex;
  justify-content: space-between;
  font-size: 0.72rem;
  color: var(--muted);
  padding: 0 2px 6px;
}
.meter-scale .center { color: var(--text); font-weight: 600; }

.meter-track {
  position: relative;
  height: 64px;
  background:
    linear-gradient(90deg,
      rgba(91, 155, 213, 0.18) 0%,
      rgba(91, 155, 213, 0.06) 35%,
      rgba(95, 208, 160, 0.22) 47%,
      rgba(95, 208, 160, 0.22) 53%,
      rgba(224, 115, 92, 0.06) 65%,
      rgba(224, 115, 92, 0.18) 100%);
  border-radius: 12px;
  overflow: hidden;
  border: 1px solid rgba(255, 255, 255, 0.06);
}
.meter-center-line {
  position: absolute;
  top: 0; bottom: 0; left: 50%;
  width: 2px;
  background: rgba(255, 255, 255, 0.35);
  transform: translateX(-1px);
}
.needle {
  position: absolute;
  top: 4px; bottom: 4px;
  width: 4px;
  left: 50%;
  background: var(--muted);
  border-radius: 4px;
  transform: translateX(-50%);
  transition: left 0.1s ease-out, background-color 0.15s ease, box-shadow 0.15s ease;
}
.needle.in-tune { background: var(--in-tune); box-shadow: 0 0 12px var(--in-tune); }
.needle.close { background: var(--amber); box-shadow: 0 0 12px var(--amber); }
.needle.off { background: var(--sharp); box-shadow: 0 0 12px var(--sharp); }

.meter-labels {
  display: flex;
  justify-content: space-between;
  font-size: 0.72rem;
  letter-spacing: 0.08em;
  color: var(--muted);
  padding: 8px 4px 0;
}

.readout {
  display: flex;
  justify-content: space-between;
  margin-top: 18px;
  font-variant-numeric: tabular-nums;
  color: var(--muted);
  font-size: 0.95rem;
}
.cents { font-weight: 600; color: var(--text); }

.signal-row {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-top: 20px;
}
.signal-label {
  font-size: 0.75rem;
  color: var(--muted);
  white-space: nowrap;
}
.signal-meter {
  flex: 1;
  height: 6px;
  border-radius: 3px;
  background: rgba(255, 255, 255, 0.06);
  overflow: hidden;
}
.signal-bar {
  height: 100%;
  width: 0%;
  background: var(--flat);
  transition: width 0.08s ease-out;
}

#waveform {
  width: 100%;
  height: 90px;
  border-radius: 10px;
  background: rgba(0, 0, 0, 0.2);
  display: block;
  margin-top: 16px;
}

.spectrum-canvas {
  width: 100%;
  height: 120px;
  border-radius: 10px;
  background: rgba(0, 0, 0, 0.2);
  display: block;
  margin-top: 16px;
}

.strings { margin-top: 8px; }
.notes-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin: 28px 0 12px;
}
.notes-header h2 { margin: 0; }
.tuning-select {
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid rgba(255, 255, 255, 0.12);
  color: var(--text);
  border-radius: 8px;
  padding: 6px 10px;
  font-size: 0.8rem;
  font-weight: 600;
  cursor: pointer;
  max-width: 55%;
}
.tuning-select:hover, .tuning-select:focus { border-color: var(--accent); outline: none; }
.tuning-select option { background: var(--panel); color: var(--text); }
.string-list {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(64px, 1fr));
  gap: 8px;
}
.string-chip {
  position: relative;
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid rgba(255, 255, 255, 0.06);
  border-radius: 10px;
  padding: 18px 4px 10px;
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--muted);
  transition: all 0.15s ease;
}
.string-chip .freq {
  display: block;
  font-size: 0.68rem;
  font-weight: 400;
  margin-top: 2px;
  color: rgba(255, 255, 255, 0.35);
}
.string-chip.active {
  color: var(--text);
  border-color: var(--accent);
  background: rgba(95, 208, 160, 0.12);
}

.string-list.auto-mode .string-chip {
  opacity: 0.4;
  transition: opacity 0.15s ease, all 0.15s ease;
}
.string-chip.auto-target {
  opacity: 1;
  border-color: var(--accent);
  box-shadow: 0 0 0 2px rgba(95, 208, 160, 0.35);
  animation: auto-target-pulse 1.4s ease-in-out infinite;
}
.string-chip.auto-done {
  opacity: 0.7;
  color: var(--accent);
}
@keyframes auto-target-pulse {
  0%, 100% { box-shadow: 0 0 0 2px rgba(95, 208, 160, 0.35); }
  50% { box-shadow: 0 0 0 5px rgba(95, 208, 160, 0.12); }
}

.custom-editor { margin-top: 4px; }
.custom-rows {
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin-bottom: 14px;
}
.custom-row {
  display: flex;
  align-items: center;
  gap: 10px;
}
.custom-row-label {
  flex: 1;
  text-align: left;
  font-size: 0.85rem;
  color: var(--muted);
}
.custom-note-select,
.custom-octave-input {
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid rgba(255, 255, 255, 0.12);
  color: var(--text);
  border-radius: 8px;
  padding: 6px 8px;
  font-size: 0.85rem;
}
.custom-note-select { flex: 1; }
.custom-octave-input { width: 56px; text-align: center; }
.custom-note-select:focus, .custom-octave-input:focus { outline: none; border-color: var(--accent); }
.apply-custom-btn {
  appearance: none;
  width: 100%;
  border: none;
  border-radius: 10px;
  padding: 10px;
  font-size: 0.9rem;
  font-weight: 600;
  background: var(--accent);
  color: #0d2018;
  cursor: pointer;
}
.apply-custom-btn:hover { transform: translateY(-1px); }
.chip-play {
  appearance: none;
  position: absolute;
  top: 1px;
  right: 1px;
  width: 24px;
  height: 24px;
  padding: 0;
  border: none;
  border-radius: 50%;
  background: none;
  color: var(--muted);
  font-size: 0.65rem;
  line-height: 24px;
  cursor: pointer;
  transition: color 0.15s ease, background 0.15s ease;
}
.chip-play:hover { color: var(--text); background: rgba(255, 255, 255, 0.08); }
.chip-play.playing { color: var(--accent); background: rgba(95, 208, 160, 0.18); }