:root {
  --black: #111;
  --white: #fff;
  --gray-100: #f4f4f4;
  --gray-300: #d4d4d4;
  --gray-500: #999;
  --gray-700: #555;
}

* {
  box-sizing: border-box;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Helvetica, Arial, sans-serif;
  color: var(--black);
  background: var(--white);
  max-width: 900px;
  margin: 0 auto;
  padding: 24px 16px 64px;
}

header h1 {
  margin: 0 0 4px;
  font-size: 1.5rem;
}

.subtitle {
  margin: 0 0 20px;
  color: var(--gray-700);
  font-size: 0.9rem;
}

/* Tabs, styled as a radio toggle group */
.tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 20px;
  border-bottom: 2px solid var(--black);
  padding-bottom: 12px;
}

.tabs input[type='radio'] {
  position: absolute;
  opacity: 0;
  width: 0;
  height: 0;
}

.tabs label {
  flex: 1 1 auto;
  text-align: center;
  padding: 10px 16px;
  border: 2px solid var(--black);
  border-radius: 4px;
  cursor: pointer;
  font-weight: 600;
  background: var(--white);
}

.tabs input[type='radio']:checked + label {
  background: var(--black);
  color: var(--white);
}

.tabs input[type='radio']:focus-visible + label {
  outline: 2px solid var(--gray-500);
  outline-offset: 2px;
}

fieldset {
  border: 1px solid var(--gray-300);
  border-radius: 6px;
  margin-bottom: 16px;
  padding: 12px 14px;
}

legend {
  font-weight: 600;
  padding: 0 6px;
}

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

/* Radio-button style option groups (tuning / root / quality) */
.option-row input[type='radio'] {
  position: absolute;
  opacity: 0;
  width: 0;
  height: 0;
}

.option-row label.choice {
  padding: 9px 13px;
  border: 1px solid var(--black);
  border-radius: 4px;
  cursor: pointer;
  background: var(--white);
  font-size: 0.9rem;
  line-height: 1.1;
}

.option-row input[type='radio']:checked + label.choice {
  background: var(--black);
  color: var(--white);
}

.option-row input[type='radio']:focus-visible + label.choice {
  outline: 2px solid var(--gray-500);
  outline-offset: 2px;
}

.fret-input-label {
  display: flex;
  align-items: center;
  gap: 8px;
  font-weight: 600;
}

.fret-input-label input[type='number'] {
  width: 64px;
  padding: 8px 6px;
  border: 1px solid var(--black);
  border-radius: 4px;
  font-size: 1rem;
}

.hint {
  color: var(--gray-700);
  font-size: 0.85rem;
}

.results {
  display: flex;
  flex-wrap: wrap;
  gap: 20px;
  margin-top: 16px;
}

.empty-message {
  color: var(--gray-700);
  font-style: italic;
}

.chord-card {
  border: 1px solid var(--gray-300);
  border-radius: 8px;
  padding: 14px;
  width: fit-content;
  text-align: center;
}

.chord-card .card-title {
  font-weight: 700;
  margin-bottom: 4px;
}

.chord-card .card-subtitle {
  color: var(--gray-700);
  font-size: 0.8rem;
  margin-bottom: 8px;
}

.chord-card .card-tags {
  display: flex;
  justify-content: center;
  gap: 4px;
  margin-top: 8px;
  flex-wrap: wrap;
}

.tag {
  border: 1px solid var(--gray-500);
  border-radius: 999px;
  padding: 1px 8px;
  font-size: 0.7rem;
  color: var(--gray-700);
}

.browse-group {
  width: 100%;
}

.browse-group h3 {
  margin: 20px 0 8px;
  font-size: 1rem;
  border-bottom: 1px solid var(--gray-300);
  padding-bottom: 4px;
}

.browse-group .results {
  margin-top: 0;
}

/* Fret diagram SVG */
.fret-diagram {
  display: block;
  margin: 0 auto;
}

.string-line {
  stroke: var(--black);
  stroke-width: 1;
}

.fret-line {
  stroke: var(--gray-500);
  stroke-width: 1;
}

.nut-line {
  stroke: var(--black);
}

.barre-line {
  stroke: var(--gray-700);
}

.fret-dot {
  fill: var(--black);
}

.open-marker {
  fill: var(--white);
  stroke: var(--black);
  stroke-width: 1.5;
}

.note-label {
  fill: var(--black);
  font-size: 11px;
}

.fret-number-label {
  fill: var(--black);
  font-size: 12px;
  font-weight: 600;
}

@media (max-width: 480px) {
  body {
    padding: 16px 12px 48px;
  }

  header h1 {
    font-size: 1.3rem;
  }

  .subtitle {
    font-size: 0.85rem;
  }

  fieldset {
    padding: 10px 12px;
    margin-bottom: 12px;
  }

  .option-row {
    gap: 6px;
  }

  .results {
    gap: 14px;
    justify-content: center;
  }

  .hint {
    flex-basis: 100%;
  }
}