/* ── Reset & Variables ─────────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --bg:         #0f1117;
  --surface:    #1a1d27;
  --surface2:   #252836;
  --border:     #2e3147;
  --text:       #e8eaf0;
  --text-dim:   #8a8fa8;
  --accent:     #6c8fff;
  --accent-dim: #3d5299;
  --green:      #2ecc71;
  --red:        #e74c3c;
  --amber:      #f39c12;
  --radius:     10px;
  --shadow:     0 4px 24px rgba(0,0,0,0.4);
  --font:       system-ui, -apple-system, 'Segoe UI', sans-serif;
}

html, body {
  height: 100%;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

/* ── Layout ──────────────────────────────────────────────────── */
#app {
  display: flex;
  flex-direction: column;
  min-height: 100dvh;
  max-width: 780px;
  margin: 0 auto;
  padding: 0 16px;
}

header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 18px 0 14px;
  border-bottom: 1px solid var(--border);
}

.logo {
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--accent);
  letter-spacing: -0.5px;
}
.logo span { color: var(--text-dim); font-weight: 400; font-size: 0.9rem; margin-left: 6px; }

.header-actions { display: flex; gap: 8px; }

main { flex: 1; padding: 24px 0 32px; }

/* ── Screens ─────────────────────────────────────────────────── */
.screen { display: none; }
.screen.active { display: block; }

/* ── Buttons ─────────────────────────────────────────────────── */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 10px 20px;
  border: none;
  border-radius: var(--radius);
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.15s, transform 0.1s, opacity 0.15s;
  font-family: var(--font);
}
.btn:active { transform: scale(0.97); }
.btn:disabled { opacity: 0.4; cursor: not-allowed; transform: none; }

.btn-primary { background: var(--accent); color: #fff; }
.btn-primary:hover:not(:disabled) { background: #7d9fff; }

.btn-secondary { background: var(--surface2); color: var(--text); border: 1px solid var(--border); }
.btn-secondary:hover:not(:disabled) { background: var(--border); }

.btn-ghost { background: transparent; color: var(--text-dim); }
.btn-ghost:hover:not(:disabled) { color: var(--text); background: var(--surface2); }

.btn-danger { background: #4a1a1a; color: var(--red); border: 1px solid #7a2a2a; }
.btn-danger:hover:not(:disabled) { background: #6a2020; }

.btn-icon { padding: 8px; border-radius: 8px; font-size: 1.1rem; }

/* ── HOME SCREEN ─────────────────────────────────────────────── */

/* Module tabs */
.module-tabs {
  display: flex;
  gap: 4px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 4px;
  margin-bottom: 24px;
}
.module-tab {
  flex: 1;
  padding: 9px 16px;
  border: none;
  border-radius: 7px;
  background: transparent;
  color: var(--text-dim);
  font-size: 0.92rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.15s, color 0.15s;
  font-family: var(--font);
}
.module-tab:hover { color: var(--text); background: var(--surface2); }
.module-tab.active { background: var(--accent); color: #fff; }

/* Single-bar mastery row for chords */
.mastery-bars--single { flex: 1; }
.mastery-bars--single .mastery-cell { max-width: 220px; }

/* Wrong-answer "you chose" line with comparison play button */
.feedback-wrong-choice {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.9rem;
  color: var(--text-dim);
  margin-top: 4px;
}
.btn-compare {
  display: inline-flex;
  align-items: center;
  gap: 3px;
  padding: 2px 9px;
  font-size: 0.78rem;
  background: transparent;
  border: 1px solid var(--border);
  border-radius: 4px;
  color: var(--text);
  cursor: pointer;
  flex-shrink: 0;
}
.btn-compare:hover { background: var(--surface-2, rgba(255,255,255,0.06)); }

/* Chord character blurb inside feedback */
.chord-character {
  font-size: 0.85rem;
  color: var(--text-dim);
  font-style: italic;
  margin-top: 4px;
  margin-bottom: 8px;
}

.home-hero {
  text-align: center;
  padding: 32px 0 28px;
}
.home-hero h1 {
  font-size: 2rem;
  font-weight: 800;
  margin-bottom: 8px;
  background: linear-gradient(135deg, var(--accent) 0%, #a78bff 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.home-hero p {
  color: var(--text-dim);
  font-size: 1rem;
  max-width: 420px;
  margin: 0 auto 24px;
}
.home-cta { display: flex; justify-content: center; gap: 12px; }
.btn-start { font-size: 1.1rem; padding: 13px 32px; }

/* Stats bar */
.stats-bar {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
  margin: 0 0 28px;
}
.stat-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 14px 12px;
  text-align: center;
}
.stat-value {
  font-size: 1.6rem;
  font-weight: 700;
  color: var(--accent);
  line-height: 1;
}
.stat-label {
  font-size: 0.72rem;
  color: var(--text-dim);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-top: 4px;
}

/* Mastery grid */
.section-title {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--text-dim);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: 12px;
}

#mastery-grid { display: flex; flex-direction: column; gap: 6px; }

.mastery-row {
  display: flex;
  align-items: center;
  gap: 12px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 10px 14px;
}
.mastery-row--inversion {
  border-style: dashed;
  opacity: 0.9;
}

.mastery-label {
  width: 80px;
  flex-shrink: 0;
}
.mastery-label .short {
  font-weight: 700;
  font-size: 0.95rem;
  color: var(--accent);
}
.mastery-label .full {
  display: block;
  font-size: 0.7rem;
  color: var(--text-dim);
  margin-top: 1px;
}

.mastery-bars {
  display: flex;
  gap: 8px;
  flex: 1;
}

.mastery-cell {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 3px;
}
.mastery-cell.locked { opacity: 0.45; }

.dir-label {
  font-size: 0.65rem;
  color: var(--text-dim);
  text-align: center;
}

.bar-track {
  height: 6px;
  background: var(--surface2);
  border-radius: 3px;
  overflow: hidden;
}
.bar-fill {
  height: 100%;
  border-radius: 3px;
  background: var(--accent);
  transition: width 0.4s ease;
  min-width: 0;
}
.bar-pct {
  font-size: 0.62rem;
  color: var(--text-dim);
  text-align: center;
}

/* ── QUESTION SCREEN ─────────────────────────────────────────── */
#screen-question {}

/* Progress bar */
.progress-bar-wrap {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 20px;
}
.progress-track {
  flex: 1;
  height: 6px;
  background: var(--surface2);
  border-radius: 3px;
  overflow: hidden;
}
#progress-fill {
  height: 100%;
  background: var(--accent);
  border-radius: 3px;
  transition: width 0.3s ease;
}
#progress-label {
  font-size: 0.8rem;
  color: var(--text-dim);
  white-space: nowrap;
  min-width: 50px;
  text-align: right;
}

/* Question header row */
.question-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 28px;
}

.direction-badge {
  padding: 5px 12px;
  border-radius: 20px;
  font-size: 0.8rem;
  font-weight: 600;
}
.dir-ascending  { background: #1a2a4a; color: #6c8fff; border: 1px solid #2a3a6a; }
.dir-descending { background: #2a1a3a; color: #c478ff; border: 1px solid #4a2a6a; }
.dir-harmonic   { background: #1a3a2a; color: #4adf9f; border: 1px solid #2a5a3a; }

#new-badge {
  background: var(--amber);
  color: #1a0a00;
  padding: 4px 10px;
  border-radius: 20px;
  font-size: 0.75rem;
  font-weight: 700;
}
#new-badge.hidden { display: none; }

/* Play area */
.play-area {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 12px;
  min-height: 90px;
  margin-bottom: 28px;
}

.btn-play-big {
  font-size: 1.15rem;
  padding: 16px 36px;
  border-radius: 50px;
  gap: 8px;
}
.play-icon { font-size: 1.4rem; }

/* Answer buttons */
#answer-buttons {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(110px, 1fr));
  gap: 10px;
  margin-bottom: 24px;
}

.answer-btn {
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 14px 8px;
  background: var(--surface);
  border: 2px solid var(--border);
  border-radius: var(--radius);
  cursor: pointer;
  transition: background 0.12s, border-color 0.12s, transform 0.1s;
  font-family: var(--font);
  gap: 2px;
  min-height: 72px;
}
.answer-btn:hover:not(:disabled) {
  background: var(--surface2);
  border-color: var(--accent-dim);
}
.answer-btn:active:not(:disabled) { transform: scale(0.96); }
.answer-btn:disabled { opacity: 0.5; cursor: not-allowed; }

.answer-btn.correct {
  background: #0d2a1a;
  border-color: var(--green);
  color: var(--green);
}
.answer-btn.wrong {
  background: #2a0d0d;
  border-color: var(--red);
  color: var(--red);
}

.key-hint {
  position: absolute;
  top: 5px;
  right: 7px;
  font-size: 0.65rem;
  color: var(--text-dim);
  background: var(--surface2);
  border-radius: 4px;
  padding: 1px 4px;
  line-height: 1.4;
}
.interval-short {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--accent);
}
.answer-btn.correct .interval-short { color: var(--green); }
.answer-btn.wrong   .interval-short { color: var(--red); }

.interval-full {
  font-size: 0.7rem;
  color: var(--text-dim);
  text-align: center;
  line-height: 1.2;
}

/* Feedback */
.feedback-area {
  background: var(--surface);
  border-radius: var(--radius);
  padding: 16px 20px;
  border-left: 4px solid var(--border);
  margin-bottom: 20px;
  transition: border-color 0.2s;
}
.feedback-area.hidden { display: none; }
.feedback-correct { border-color: var(--green); background: #0d2a1a; }
.feedback-wrong   { border-color: var(--red);   background: #2a0d0d; }

.feedback-icon {
  font-size: 1.6rem;
  line-height: 1;
  margin-bottom: 6px;
}
.feedback-correct .feedback-icon { color: var(--green); }
.feedback-wrong   .feedback-icon { color: var(--red); }

.feedback-text {
  font-size: 1rem;
  color: var(--text);
  margin-bottom: 10px;
}
.feedback-text strong { color: var(--accent); }

.songs-section { margin-top: 12px; }
.songs-title {
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-dim);
  margin-bottom: 6px;
}
.songs-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 4px;
}
.songs-list li {
  font-size: 0.88rem;
  color: var(--text-dim);
  padding: 4px 0;
  border-bottom: 1px solid var(--border);
}
.songs-list li:last-child { border-bottom: none; }
.songs-list strong { color: var(--text); }

.question-actions {
  display: flex;
  justify-content: flex-end;
  gap: 10px;
}

/* ── SUMMARY SCREEN ──────────────────────────────────────────── */
#screen-summary { max-width: 520px; margin: 0 auto; }

.summary-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 28px 24px;
  text-align: center;
  margin-bottom: 16px;
  transition: border-color 0.3s, box-shadow 0.3s;
}
.summary-card--perfect {
  border-color: #f1c40f;
  box-shadow: 0 0 24px rgba(241, 196, 15, 0.25);
}

#summary-emoji { font-size: 3rem; margin-bottom: 8px; }
#summary-score { font-size: 2.4rem; font-weight: 800; color: var(--text); }
#summary-pct {
  font-size: 1.1rem;
  color: var(--text-dim);
  margin-bottom: 4px;
}
#summary-perfect-label {
  font-size: 0.85rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: #f1c40f;
  margin-bottom: 16px;
}
#summary-perfect-label.hidden { display: none; }

#summary-unlocks, #summary-changes {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px 20px;
  margin-bottom: 14px;
}
#summary-unlocks.hidden, #summary-changes.hidden { display: none; }

#summary-unlocks h3, #summary-changes h3 {
  font-size: 0.8rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-dim);
  margin-bottom: 10px;
}
#summary-unlocks ul { list-style: none; }
#summary-unlocks li { padding: 5px 0; font-size: 0.95rem; color: var(--amber); }

.change-row {
  display: flex;
  justify-content: space-between;
  padding: 5px 0;
  font-size: 0.9rem;
  border-bottom: 1px solid var(--border);
}
.change-row:last-child { border-bottom: none; }

/* Unlock prompt in summary screen */
.unlock-prompt {
  background: var(--surface);
  border: 1px solid var(--accent);
  border-radius: 12px;
  padding: 16px 20px;
  margin-bottom: 16px;
  text-align: center;
}
.unlock-prompt-title {
  font-size: 0.85rem;
  color: var(--text-dim);
  margin-bottom: 6px;
}
.unlock-prompt-names {
  font-size: 1.1rem;
  margin-bottom: 14px;
}
.unlock-prompt-actions {
  display: flex;
  gap: 10px;
  justify-content: center;
}

/* Manual unlock button on locked mastery rows */
.btn-manual-unlock {
  font-size: 0.72rem;
  padding: 2px 8px;
  background: transparent;
  border: 1px dashed var(--border);
  border-radius: 4px;
  color: var(--text-dim);
  cursor: pointer;
  white-space: nowrap;
  flex-shrink: 0;
}
.btn-manual-unlock:hover {
  border-color: var(--accent);
  color: var(--accent);
}
.btn-relock {
  font-size: 0.7rem;
  padding: 1px 4px;
  background: transparent;
  border: none;
  color: var(--text-dim);
  cursor: pointer;
  opacity: 0;
  transition: opacity 0.15s;
  flex-shrink: 0;
}
.mastery-cell:hover .btn-relock { opacity: 0.6; }
.btn-relock:hover { opacity: 1 !important; }

.summary-actions {
  display: flex;
  gap: 10px;
  justify-content: center;
  margin-top: 20px;
}

/* ── SETTINGS SCREEN ─────────────────────────────────────────── */
#screen-settings { max-width: 520px; }

.settings-title {
  font-size: 1.2rem;
  font-weight: 700;
  margin-bottom: 24px;
}

.setting-group {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  margin-bottom: 14px;
}
.setting-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 18px;
  border-bottom: 1px solid var(--border);
}
.setting-row:last-child { border-bottom: none; }
.setting-label { font-size: 0.93rem; }
.setting-desc {
  font-size: 0.75rem;
  color: var(--text-dim);
  margin-top: 2px;
}

/* Toggle switch */
.toggle {
  position: relative;
  width: 40px;
  height: 22px;
  flex-shrink: 0;
}
.toggle input { opacity: 0; width: 0; height: 0; }
.toggle-slider {
  position: absolute;
  inset: 0;
  background: var(--surface2);
  border-radius: 22px;
  cursor: pointer;
  border: 1px solid var(--border);
  transition: background 0.2s;
}
.toggle-slider::before {
  content: '';
  position: absolute;
  width: 16px; height: 16px;
  left: 2px; bottom: 2px;
  background: var(--text-dim);
  border-radius: 50%;
  transition: transform 0.2s, background 0.2s;
}
.toggle input:checked + .toggle-slider { background: var(--accent); border-color: var(--accent); }
.toggle input:checked + .toggle-slider::before {
  transform: translateX(18px);
  background: #fff;
}

/* Select */
.setting-select {
  background: var(--surface2);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 6px 10px;
  font-size: 0.88rem;
  cursor: pointer;
}

.settings-section-label {
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-dim);
  padding: 14px 18px 6px;
}

.settings-danger {
  background: var(--surface);
  border: 1px solid #4a2020;
  border-radius: var(--radius);
  padding: 14px 18px;
  margin-top: 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.settings-actions {
  display: flex;
  gap: 10px;
  margin-top: 24px;
}

/* ── TOAST ───────────────────────────────────────────────────── */
.toast {
  position: fixed;
  bottom: 24px;
  left: 50%;
  transform: translateX(-50%) translateY(20px);
  padding: 10px 20px;
  border-radius: 24px;
  font-size: 0.88rem;
  font-weight: 600;
  opacity: 0;
  transition: opacity 0.25s, transform 0.25s;
  z-index: 9999;
  pointer-events: none;
  white-space: nowrap;
}
.toast.show { opacity: 1; transform: translateX(-50%) translateY(0); }
.toast-success { background: #0d2a1a; color: var(--green); border: 1px solid var(--green); }
.toast-error   { background: #2a0d0d; color: var(--red);   border: 1px solid var(--red); }
.toast-info    { background: var(--surface2); color: var(--text); border: 1px solid var(--border); }

/* ── Utilities ───────────────────────────────────────────────── */
.hidden { display: none !important; }

/* ── Responsive ──────────────────────────────────────────────── */
@media (max-width: 540px) {
  .stats-bar { grid-template-columns: repeat(2, 1fr); }
  #answer-buttons { grid-template-columns: repeat(auto-fill, minmax(90px, 1fr)); gap: 8px; }
  .mastery-label .full { display: none; }
  .mastery-label { width: 44px; }
  .home-hero h1 { font-size: 1.6rem; }
}