:root {
  --bg: #f4f5f7;
  --card-bg: #ffffff;
  --text: #1a1d23;
  --text-muted: #6b7280;
  --border: #e3e6ea;
  --border-strong: #c7ccd3;
  --accent: #4f46e5;
  --accent-text: #ffffff;
  --accent-soft: #eef0fe;
  --shadow: 0 1px 2px rgba(15, 17, 21, 0.04), 0 8px 24px rgba(15, 17, 21, 0.06);
  --radius: 14px;
  --radius-sm: 10px;
  --focus-ring: 0 0 0 3px rgba(79, 70, 229, 0.35);
}

[data-theme="dark"] {
  --bg: #0f1115;
  --card-bg: #181b21;
  --text: #f1f3f5;
  --text-muted: #9aa3af;
  --border: #2a2f38;
  --border-strong: #3a414c;
  --accent: #818cf8;
  --accent-text: #0f1115;
  --accent-soft: #232636;
  --shadow: 0 1px 2px rgba(0, 0, 0, 0.4), 0 8px 30px rgba(0, 0, 0, 0.45);
  --focus-ring: 0 0 0 3px rgba(129, 140, 248, 0.45);
}

* { box-sizing: border-box; }

html, body { height: 100%; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  font-size: 16px;
  line-height: 1.4;
  color: var(--text);
  background: var(--bg);
  min-height: 100dvh;
  display: flex;
  flex-direction: column;
}

.topbar {
  width: 100%;
  padding: 12px max(16px, env(safe-area-inset-right)) 12px max(16px, env(safe-area-inset-left));
  padding-top: max(12px, env(safe-area-inset-top));
}
.topbar-inner {
  max-width: 960px;
  margin: 0 auto;
  display: flex;
  justify-content: flex-end;
  align-items: center;
  gap: 10px;
}

main {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 8px 16px 16px;
  padding-bottom: max(16px, env(safe-area-inset-bottom));
}

.card {
  width: 100%;
  max-width: 460px;
  background: var(--card-bg);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 28px;
  display: flex;
  flex-direction: column;
  gap: 22px;
}

.card-header h1 {
  margin: 0 0 4px 0;
  font-size: 1.55rem;
  font-weight: 650;
  letter-spacing: -0.01em;
}
.card-header .subtitle {
  margin: 0;
  color: var(--text-muted);
  font-size: 0.95rem;
}
.lang-switch, .theme-switch { padding: 3px; }
.lang-switch label, .theme-switch label { flex: 0 0 auto; }
.lang-switch label span {
  min-height: 30px;
  padding: 0 10px;
  font-size: 1.05rem;
  font-weight: 500;
  letter-spacing: normal;
  line-height: 1;
}
.theme-switch label span {
  min-height: 30px;
  padding: 0 10px;
  color: var(--text-muted);
}
.theme-switch input[type="radio"]:checked + span { color: var(--text); }

.field { display: flex; flex-direction: column; gap: 10px; }
.field-label {
  font-size: 0.82rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-muted);
  font-weight: 600;
}

/* Segmented radio control */
.segmented {
  display: flex;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 4px;
  gap: 4px;
}
.segmented label {
  flex: 1;
  position: relative;
}
.segmented input[type="radio"] {
  position: absolute;
  opacity: 0;
  pointer-events: none;
}
.segmented label span {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 38px;
  padding: 0 10px;
  border-radius: 8px;
  font-size: 0.95rem;
  color: var(--text-muted);
  font-weight: 500;
  cursor: pointer;
  user-select: none;
  transition: background 0.15s ease, color 0.15s ease;
}
.segmented label:hover span { color: var(--text); }
.segmented input[type="radio"]:checked + span {
  background: var(--card-bg);
  color: var(--text);
  box-shadow: 0 1px 2px rgba(0,0,0,0.06), 0 1px 1px rgba(0,0,0,0.03);
  font-weight: 600;
}
.segmented input[type="radio"]:focus-visible + span { box-shadow: var(--focus-ring); }

/* Tempo */
.tempo-row {
  display: flex;
  align-items: center;
  gap: 10px;
}
.tempo-step {
  font-family: inherit;
  font-size: 1.4rem;
  font-weight: 500;
  line-height: 1;
  width: 2.5rem;
  height: 2.5rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--bg);
  color: var(--text);
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  user-select: none;
  transition: background 0.12s ease, border-color 0.12s ease, transform 0.06s ease;
}
.tempo-step:hover { background: var(--accent-soft); border-color: var(--border-strong); }
.tempo-step:active { transform: translateY(1px); }
.tempo-step:focus-visible { outline: none; box-shadow: var(--focus-ring); border-color: var(--accent); }
#tempo-number {
  font-family: inherit;
  font-size: 1.8rem;
  font-weight: 600;
  width: 5ch;
  padding: 4px 8px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--bg);
  color: var(--text);
  text-align: center;
  -moz-appearance: textfield;
}
#tempo-number::-webkit-outer-spin-button,
#tempo-number::-webkit-inner-spin-button { -webkit-appearance: none; margin: 0; }
#tempo-number:focus-visible { outline: none; box-shadow: var(--focus-ring); border-color: var(--accent); }
.unit { color: var(--text-muted); font-size: 0.95rem; }

/* Play button */
.play-btn {
  margin-top: 6px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  min-height: 54px;
  padding: 0 24px;
  font-family: inherit;
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--accent-text);
  background: var(--accent);
  border: none;
  border-radius: var(--radius-sm);
  cursor: pointer;
  letter-spacing: 0.01em;
  transition: transform 0.06s ease, opacity 0.15s ease, filter 0.15s ease;
}
.play-btn:hover:not(:disabled) { filter: brightness(1.05); }
.play-btn:active:not(:disabled) { transform: translateY(1px); }
.play-btn:focus-visible { outline: none; box-shadow: var(--focus-ring); }
.play-btn:disabled {
  opacity: 0.55;
  cursor: progress;
}
.play-btn svg { display: block; }

/* Melodic-only block: stack child fields with the same gap as the card */
#melodic-controls {
  display: flex;
  flex-direction: column;
  gap: 22px;
}
#melodic-controls.hidden { display: none; }

/* Hidden view (overrides .card's display: flex) */
.view[hidden] { display: none; }

/* Game-view timer (Timed / Streak modes) */
.game-timer {
  text-align: center;
  font-size: 1.5rem;
  font-weight: 650;
  font-variant-numeric: tabular-nums;
  color: var(--text);
  margin-top: -4px;
  transition: color 0.2s ease;
}
.game-timer[hidden] { display: none; }
.game-timer.timed-low { color: #dc2626; }
.game-timer.frozen { color: var(--text-muted); }
[data-theme="dark"] .game-timer.timed-low { color: #f87171; }

/* Score badges (game view) */
.score {
  display: flex;
  justify-content: center;
  gap: 14px;
  margin-top: -6px;
}
.score-item {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 14px;
  border-radius: 999px;
  font-size: 0.95rem;
  font-weight: 600;
}
.score-correct { background: rgba(16, 185, 129, 0.14); color: #059669; }
.score-wrong   { background: rgba(239, 68, 68, 0.14);  color: #dc2626; }
[data-theme="dark"] .score-correct { background: rgba(52, 211, 153, 0.16); color: #34d399; }
[data-theme="dark"] .score-wrong   { background: rgba(248, 113, 113, 0.16); color: #f87171; }
.score-count { font-variant-numeric: tabular-nums; min-width: 1.5ch; text-align: right; }
.score-item svg { display: block; }

/* Game view controls */
.game-controls {
  display: flex;
  align-items: stretch;
  gap: 10px;
}
.game-controls .play-btn { flex: 1; margin-top: 0; }
.nav-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 54px;
  padding: 0 18px;
  font-family: inherit;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--bg);
  color: var(--text);
  cursor: pointer;
  transition: background 0.15s ease, border-color 0.15s ease, transform 0.06s ease, opacity 0.15s ease;
}
.nav-btn:hover:not(:disabled) { background: var(--accent-soft); border-color: var(--border-strong); }
.nav-btn:active:not(:disabled) { transform: translateY(1px); }
.nav-btn:focus-visible { outline: none; box-shadow: var(--focus-ring); border-color: var(--accent); }
.nav-btn:disabled { opacity: 0.35; cursor: not-allowed; }
.nav-btn svg { display: block; }

/* Interval grid — piano-keyboard layout (shared by game guess buttons and
   the configuration "allowed intervals" toggle panel).
   16 columns: every white key (bottom row) takes 2 cols starting at an odd col;
   every black key (top row) takes 2 cols starting at an even col, so it sits
   visually between the two white keys it falls between. */
.interval-grid {
  display: grid;
  grid-template-columns: repeat(16, 1fr);
  grid-auto-rows: auto;
  gap: 6px;
}
/* Top row: minor / tritone (the "black keys") */
.interval-grid > [data-interval="1"]  { grid-column: 2 / span 2;  grid-row: 1; }
.interval-grid > [data-interval="3"]  { grid-column: 4 / span 2;  grid-row: 1; }
.interval-grid > [data-interval="6"]  { grid-column: 8 / span 2;  grid-row: 1; }
.interval-grid > [data-interval="8"]  { grid-column: 10 / span 2; grid-row: 1; }
.interval-grid > [data-interval="10"] { grid-column: 12 / span 2; grid-row: 1; }
/* Bottom row: unison / major / perfect / octave (the "white keys") */
.interval-grid > [data-interval="0"]  { grid-column: 1 / span 2;  grid-row: 2; }
.interval-grid > [data-interval="2"]  { grid-column: 3 / span 2;  grid-row: 2; }
.interval-grid > [data-interval="4"]  { grid-column: 5 / span 2;  grid-row: 2; }
.interval-grid > [data-interval="5"]  { grid-column: 7 / span 2;  grid-row: 2; }
.interval-grid > [data-interval="7"]  { grid-column: 9 / span 2;  grid-row: 2; }
.interval-grid > [data-interval="9"]  { grid-column: 11 / span 2; grid-row: 2; }
.interval-grid > [data-interval="11"] { grid-column: 13 / span 2; grid-row: 2; }
.interval-grid > [data-interval="12"] { grid-column: 15 / span 2; grid-row: 2; }
.guess-btn, .interval-toggle {
  font-family: inherit;
  font-size: 0.9rem;
  font-weight: 600;
  min-height: 46px;
  padding: 0 4px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--bg);
  color: var(--text);
  cursor: pointer;
  transition: background 0.15s ease, color 0.15s ease, border-color 0.15s ease, transform 0.06s ease, opacity 0.15s ease;
}
.guess-btn:hover:not(:disabled),
.interval-toggle:hover { background: var(--accent-soft); border-color: var(--border-strong); }
.guess-btn:active:not(:disabled),
.interval-toggle:active { transform: translateY(1px); }
.guess-btn:focus-visible,
.interval-toggle:focus-visible { outline: none; box-shadow: var(--focus-ring); border-color: var(--accent); }
.guess-btn:disabled:not(.guess-correct):not(.guess-wrong):not(.guess-disabled) { opacity: 0.4; cursor: not-allowed; }
.guess-btn.guess-correct {
  background: #10b981;
  border-color: #059669;
  color: #ffffff;
  opacity: 1;
}
.guess-btn.guess-wrong {
  background: #ef4444;
  border-color: #dc2626;
  color: #ffffff;
  opacity: 1;
}
.guess-btn.guess-disabled {
  opacity: 0.22;
  text-decoration: line-through;
  cursor: not-allowed;
}
[data-theme="dark"] .guess-btn.guess-correct { background: #059669; border-color: #047857; }
[data-theme="dark"] .guess-btn.guess-wrong { background: #dc2626; border-color: #b91c1c; }

/* Allowed-intervals toggles (configuration view) */
.interval-toggle[aria-pressed="true"] {
  background: var(--accent-soft);
  border-color: var(--border-strong);
}
.interval-toggle[aria-pressed="false"] {
  opacity: 0.32;
  text-decoration: line-through;
}

/* Exercise list (home view) */
.exercise-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
}
.exercise-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  padding: 16px 18px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  color: var(--text);
  text-decoration: none;
  transition: background 0.15s ease, transform 0.06s ease, border-color 0.15s ease;
}
.exercise-item:hover { background: var(--accent-soft); border-color: var(--border-strong); }
.exercise-item:active { transform: translateY(1px); }
.exercise-item:focus-visible { outline: none; box-shadow: var(--focus-ring); border-color: var(--accent); }
.exercise-text h2 { margin: 0 0 3px 0; font-size: 1.05rem; font-weight: 600; }
.exercise-text p { margin: 0; color: var(--text-muted); font-size: 0.9rem; }
.exercise-item .chevron { color: var(--text-muted); flex: 0 0 auto; }

.secondary-btn {
  align-self: center;
  background: transparent;
  border: 1px solid var(--border);
  color: var(--text-muted);
  padding: 8px 18px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  font-family: inherit;
  font-size: 0.9rem;
  font-weight: 500;
  transition: background 0.15s ease, color 0.15s ease, border-color 0.15s ease;
}
.secondary-btn:hover { background: var(--accent-soft); border-color: var(--border-strong); color: var(--text); }
.secondary-btn:focus-visible { outline: none; box-shadow: var(--focus-ring); border-color: var(--accent); }

.note-suffix { font-weight: 400; opacity: 0.82; }

/* Musical staff (game view, shown after a guess) */
.staff { display: flex; justify-content: center; margin-top: 4px; }
.staff[hidden] { display: none; }
.staff svg { width: 100%; max-width: 280px; height: auto; color: var(--text); }

/* Results view */
#results-content { display: flex; flex-direction: column; gap: 22px; }
.results-stats {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 10px 14px;
}
.results-stats .stat {
  display: flex;
  flex-direction: column;
  gap: 2px;
  padding: 10px 12px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
}
.results-stats .stat-label {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-muted);
  font-weight: 600;
}
.results-stats .stat-value {
  font-size: 1.25rem;
  font-weight: 650;
  font-variant-numeric: tabular-nums;
}
.results-stats .stat-value.correct { color: #059669; }
.results-stats .stat-value.wrong { color: #dc2626; }
[data-theme="dark"] .results-stats .stat-value.correct { color: #34d399; }
[data-theme="dark"] .results-stats .stat-value.wrong { color: #f87171; }
.results-section {
  margin: 0;
  font-size: 0.82rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-muted);
  font-weight: 600;
}

/* Per-interval bar chart */
.results-chart { display: flex; flex-direction: column; gap: 6px; }
.chart-row {
  display: grid;
  grid-template-columns: 42px 1fr 64px;
  gap: 10px;
  align-items: center;
  font-variant-numeric: tabular-nums;
}
.chart-label { text-align: right; font-weight: 600; font-size: 0.9rem; color: var(--text-muted); }
.chart-bar-track {
  display: flex;
  height: 14px;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 999px;
  overflow: hidden;
}
.chart-bar { height: 100%; }
.chart-bar.correct { background: #10b981; }
.chart-bar.wrong { background: #ef4444; }
[data-theme="dark"] .chart-bar.correct { background: #059669; }
[data-theme="dark"] .chart-bar.wrong { background: #dc2626; }
.chart-counts { font-size: 0.85rem; color: var(--text-muted); }
.chart-counts .ok { color: #059669; font-weight: 650; }
.chart-counts .ko { color: #dc2626; font-weight: 650; }
[data-theme="dark"] .chart-counts .ok { color: #34d399; }
[data-theme="dark"] .chart-counts .ko { color: #f87171; }

/* History table */
.results-table-wrap { overflow-x: auto; }
.results-table { width: 100%; border-collapse: collapse; font-size: 0.92rem; }
.results-table th, .results-table td { padding: 8px 10px; text-align: left; border-bottom: 1px solid var(--border); }
.results-table th { font-size: 0.78rem; text-transform: uppercase; letter-spacing: 0.05em; color: var(--text-muted); font-weight: 600; }
.results-table td { font-variant-numeric: tabular-nums; }
.results-table .result-correct { color: #059669; font-weight: 700; }
.results-table .result-wrong { color: #dc2626; font-weight: 700; }
[data-theme="dark"] .results-table .result-correct { color: #34d399; }
[data-theme="dark"] .results-table .result-wrong { color: #f87171; }
.results-empty { color: var(--text-muted); text-align: center; padding: 20px; }

/* Debug-view custom note picker */
.note-display {
  font-size: 1.6rem;
  font-weight: 650;
  font-variant-numeric: tabular-nums;
  text-align: center;
  letter-spacing: 0.02em;
}
.note-row {
  display: flex;
  align-items: center;
  gap: 10px;
}
.note-row input[type="range"] { flex: 1; }

input[type="range"] {
  -webkit-appearance: none;
  appearance: none;
  width: 100%;
  height: 6px;
  border-radius: 999px;
  background: var(--border);
  outline: none;
}
input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 22px; height: 22px;
  border-radius: 50%;
  background: var(--accent);
  cursor: pointer;
  border: 3px solid var(--card-bg);
  box-shadow: 0 1px 3px rgba(0,0,0,0.18);
  transition: transform 0.1s ease;
}
input[type="range"]::-moz-range-thumb {
  width: 22px; height: 22px;
  border-radius: 50%;
  background: var(--accent);
  cursor: pointer;
  border: 3px solid var(--card-bg);
  box-shadow: 0 1px 3px rgba(0,0,0,0.18);
}
input[type="range"]:active::-webkit-slider-thumb { transform: scale(1.08); }
input[type="range"]:focus-visible { box-shadow: var(--focus-ring); }

/* Back button (exercise view) */
.card-header-with-back { position: relative; }
.back-btn {
  align-self: flex-start;
  background: none;
  border: none;
  color: var(--text-muted);
  font-family: inherit;
  font-size: 0.92rem;
  font-weight: 500;
  cursor: pointer;
  padding: 4px 8px 4px 4px;
  margin: -4px 0 8px -4px;
  display: inline-flex;
  align-items: center;
  gap: 4px;
  border-radius: 8px;
  transition: background 0.15s ease, color 0.15s ease;
}
.back-btn:hover { color: var(--text); background: var(--accent-soft); }
.back-btn:focus-visible { outline: none; box-shadow: var(--focus-ring); color: var(--text); }

/* Small phone tweaks */
@media (max-width: 420px) {
  .card { padding: 22px 18px; gap: 18px; }
  .card-header h1 { font-size: 1.4rem; }
  .segmented label span { font-size: 0.9rem; min-height: 40px; }
  #tempo-number { font-size: 1.6rem; }
  .interval-grid { gap: 4px; }
  .guess-btn, .interval-toggle { font-size: 0.78rem; min-height: 42px; padding: 0 2px; }
}

/* Desktop / wide tablet: roomier card and controls */
@media (min-width: 720px) {
  main { padding: 24px 32px 40px; }
  .card {
    max-width: 560px;
    padding: 44px 48px;
    gap: 30px;
    border-radius: 18px;
  }
  #melodic-controls { gap: 30px; }
  .card-header h1 { font-size: 1.85rem; margin-bottom: 6px; }
  .card-header .subtitle { font-size: 1rem; }
  .field { gap: 12px; }
  .field-label { font-size: 0.85rem; }
  .segmented { padding: 5px; gap: 5px; }
  .segmented label span { min-height: 44px; font-size: 1rem; }
  .tempo-row { gap: 14px; }
  .tempo-step { width: 2.75rem; height: 2.75rem; font-size: 1.5rem; }
  #tempo-number { font-size: 2rem; }
  .play-btn { min-height: 60px; font-size: 1.1rem; margin-top: 10px; }
  .nav-btn { min-height: 60px; padding: 0 22px; }
  .game-controls .play-btn { margin-top: 0; }
  .interval-grid { gap: 10px; }
  .guess-btn, .interval-toggle { min-height: 52px; font-size: 1rem; }
}