:root {
  --bg: #f4f5f7;
  --card: #ffffff;
  --text: #1c1e21;
  --muted: #5f646b;
  --border: #dfe2e6;
  --accent: #1f5fa8;
  --ok: #1a7f37;
  --bad: #b42318;
  font-family: system-ui, -apple-system, 'Segoe UI', Roboto, sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.45;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
}

.app {
  max-width: 1100px;
  margin: 0 auto;
  padding: 16px 16px 48px;
}

.app-header h1 {
  margin: 8px 0 4px;
  font-size: 1.7rem;
}

.app-header p,
.hint {
  color: var(--muted);
  margin: 0 0 16px;
  max-width: 70em;
}

.app-footer {
  color: var(--muted);
  font-size: 0.85rem;
  margin-top: 16px;
}

.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 14px 16px 16px;
  margin-bottom: 16px;
}

.card h2 {
  margin: 0 0 10px;
  font-size: 1.15rem;
}

.card h3 {
  margin: 0;
  font-size: 0.95rem;
  color: var(--muted);
  font-weight: 600;
}

.tone {
  border-top: 4px solid;
  flex: 1 1 380px;
  min-width: 0;
}

.tone-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
}

.columns {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
  margin-bottom: 16px;
}

.columns .card {
  margin-bottom: 0;
}

.plot {
  display: block;
  width: 100%;
  background: #fff;
}

.waveform-plot {
  height: 170px;
}

.stem-plot {
  height: 120px;
}

.plot-label {
  font-size: 0.8rem;
  color: var(--muted);
  margin: 10px 0 2px;
}

.controls-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 8px;
  margin: 14px 0 6px;
}

.button-row {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
}

.spacer {
  flex: 1;
}

button {
  font: inherit;
  font-size: 0.9rem;
  padding: 6px 12px;
  border-radius: 6px;
  border: 1px solid var(--border);
  background: #fff;
  color: var(--text);
  cursor: pointer;
}

button:hover:not(:disabled) {
  background: #f0f2f5;
}

button:disabled {
  opacity: 0.5;
  cursor: default;
}

button.primary {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}

button.primary:hover:not(:disabled) {
  background: #184c87;
}

button.answer {
  font-weight: 600;
  min-width: 100px;
}

button.small {
  font-size: 0.8rem;
  padding: 4px 10px;
}

.playing-indicator {
  color: var(--muted);
  font-size: 0.9rem;
  min-width: 8em;
}

.global-controls {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 24px;
  align-items: center;
}

.global-controls label {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.9rem;
}

.global-controls label > span {
  white-space: nowrap;
}

.f0-range {
  width: 180px;
}

select {
  font: inherit;
  font-size: 0.9rem;
  padding: 4px 6px;
  border-radius: 6px;
  border: 1px solid var(--border);
  background: #fff;
}

.slider-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 2px 24px;
}

.slider-row {
  display: grid;
  grid-template-columns: 1.6em 1fr 5.5em 1.2em;
  align-items: center;
  gap: 6px;
}

.slider-label {
  font-variant-numeric: tabular-nums;
  color: var(--muted);
  font-size: 0.85rem;
  text-align: right;
}

.slider-unit {
  color: var(--muted);
  font-size: 0.85rem;
}

input[type='range'] {
  width: 100%;
  min-width: 80px;
  accent-color: var(--accent);
}

.slider-value {
  font: inherit;
  font-size: 0.85rem;
  width: 5.5em;
  padding: 2px 4px;
  border: 1px solid var(--border);
  border-radius: 4px;
}

.blind-controls {
  margin: 8px 0;
}

.feedback {
  min-height: 1.6em;
  margin: 6px 0 12px;
  font-size: 0.95rem;
}

.feedback .ok {
  color: var(--ok);
  font-weight: 600;
}

.feedback .bad {
  color: var(--bad);
  font-weight: 600;
}

.stats {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 28px;
  align-items: flex-end;
  padding-top: 10px;
  border-top: 1px solid var(--border);
}

.stats > div {
  display: flex;
  flex-direction: column;
}

.stat-label {
  font-size: 0.75rem;
  color: var(--muted);
}

.stat-value {
  font-size: 1.15rem;
  font-variant-numeric: tabular-nums;
}

.stat-value small {
  font-size: 0.8rem;
  color: var(--muted);
}

kbd {
  font-family: inherit;
  font-size: 0.85em;
  border: 1px solid var(--border);
  border-bottom-width: 2px;
  border-radius: 4px;
  padding: 0 5px;
  background: #fafbfc;
}

.cycle-controls {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 8px 20px;
  margin: 4px 0 12px;
}

.cycle-controls label {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.9rem;
}

.cycle-controls label > span {
  white-space: nowrap;
}

.cycle-range {
  width: 220px;
}

.cycle-period {
  color: var(--muted);
  font-variant-numeric: tabular-nums;
}

.cycle-position {
  display: flex;
  align-items: center;
  gap: 10px;
  max-width: 520px;
}

.cycle-end {
  font-weight: 700;
}

.cycle-a {
  color: #1f5fa8;
}

.cycle-b {
  color: #d9641e;
}

.cycle-track {
  position: relative;
  flex: 1;
  height: 8px;
  border-radius: 4px;
  background: linear-gradient(90deg, #1f5fa8, #d9641e);
}

.cycle-marker {
  position: absolute;
  top: 50%;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: #fff;
  border: 2px solid var(--text);
  transform: translate(-50%, -50%);
  transition: opacity 0.2s;
}

.error {
  color: var(--bad);
  margin-top: 8px;
  font-size: 0.9rem;
}

@media (max-width: 600px) {
  .slider-row {
    grid-template-columns: 1.6em 1fr 4.5em 1.2em;
  }
}