/* style.css — Number Listening Trainer v2
   Mobile-first, CSS Custom Properties, dark theme, grouped categories */

/* ── Reset & Base ─────────────────────────────────────────────────────── */

*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --color-bg: #f5f5f7;
  --color-surface: #ffffff;
  --color-text: #1d1d1f;
  --color-text-secondary: #6e6e73;
  --color-primary: #007aff;
  --color-primary-hover: #0051d5;
  --color-correct: #34c759;
  --color-correct-bg: #d4f5dd;
  --color-wrong: #ff3b30;
  --color-wrong-bg: #fddcda;
  --color-border: #d2d2d7;
  --color-btn-bg: #ffffff;
  --color-speed-active: #007aff;
  --color-speed-text: #ffffff;
  --color-group-header: #6e6e73;
  --radius: 12px;
  --radius-sm: 8px;
  --shadow: 0 1px 3px rgba(0,0,0,0.08);
  --shadow-lg: 0 4px 12px rgba(0,0,0,0.12);
  --font: -apple-system, BlinkMacSystemFont, 'SF Pro Text', 'Helvetica Neue', sans-serif;
  --safe-bottom: env(safe-area-inset-bottom, 0px);
}

/* ── Dark theme: system preference (auto) ─────────────────────────────── */

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --color-bg: #1c1c1e;
    --color-surface: #2c2c2e;
    --color-text: #f5f5f7;
    --color-text-secondary: #aeaeb2;
    --color-border: #48484a;
    --color-btn-bg: #3a3a3c;
    --color-correct-bg: #1b3a26;
    --color-wrong-bg: #3a1b1b;
    --color-group-header: #aeaeb2;
    --shadow: 0 1px 3px rgba(0,0,0,0.3);
    --shadow-lg: 0 4px 12px rgba(0,0,0,0.4);
  }
}

/* ── Dark theme: forced ───────────────────────────────────────────────── */

:root[data-theme="dark"] {
  --color-bg: #1c1c1e;
  --color-surface: #2c2c2e;
  --color-text: #f5f5f7;
  --color-text-secondary: #aeaeb2;
  --color-border: #48484a;
  --color-btn-bg: #3a3a3c;
  --color-correct-bg: #1b3a26;
  --color-wrong-bg: #3a1b1b;
  --color-group-header: #aeaeb2;
  --shadow: 0 1px 3px rgba(0,0,0,0.3);
  --shadow-lg: 0 4px 12px rgba(0,0,0,0.4);
}

/* ── Light theme: forced ──────────────────────────────────────────────── */

:root[data-theme="light"] {
  --color-bg: #f5f5f7;
  --color-surface: #ffffff;
  --color-text: #1d1d1f;
  --color-text-secondary: #6e6e73;
  --color-border: #d2d2d7;
  --color-btn-bg: #ffffff;
  --color-correct-bg: #d4f5dd;
  --color-wrong-bg: #fddcda;
  --color-group-header: #6e6e73;
  --shadow: 0 1px 3px rgba(0,0,0,0.08);
  --shadow-lg: 0 4px 12px rgba(0,0,0,0.12);
}

html {
  font-family: var(--font);
  font-size: 16px;
  color: var(--color-text);
  background: var(--color-bg);
  -webkit-text-size-adjust: 100%;
  -webkit-tap-highlight-color: transparent;
}

body {
  min-height: 100vh;
  min-height: 100dvh;
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 0 16px;
  padding-bottom: var(--safe-bottom);
}

/* ── Screens ──────────────────────────────────────────────────────────── */

.screen {
  display: none;
  width: 100%;
  max-width: 400px;
  flex: 1;
  flex-direction: column;
  padding: 24px 0;
}

.screen.active {
  display: flex;
}

/* ── Typography ───────────────────────────────────────────────────────── */

h1 {
  font-size: 1.75rem;
  font-weight: 700;
  margin-bottom: 16px;
  text-align: center;
}

h2 {
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: 12px;
  text-align: center;
}

p {
  line-height: 1.5;
  color: var(--color-text-secondary);
  margin-bottom: 12px;
}

/* ── Buttons (common) ─────────────────────────────────────────────────── */

button {
  font-family: var(--font);
  font-size: 1rem;
  cursor: pointer;
  border: none;
  border-radius: var(--radius);
  transition: background-color 0.15s, transform 0.1s;
  -webkit-appearance: none;
  touch-action: manipulation;
}

button:active {
  transform: scale(0.97);
}

button:disabled {
  opacity: 0.5;
  cursor: default;
  transform: none;
}

/* ── Primary button ───────────────────────────────────────────────────── */

.btn-primary {
  display: block;
  width: 100%;
  padding: 16px;
  background: var(--color-primary);
  color: #fff;
  font-size: 1.125rem;
  font-weight: 600;
  box-shadow: var(--shadow);
}

.btn-primary:active {
  background: var(--color-primary-hover);
}

/* ── Secondary button ─────────────────────────────────────────────────── */

.btn-secondary {
  display: block;
  width: 100%;
  padding: 14px;
  background: var(--color-surface);
  color: var(--color-primary);
  font-weight: 600;
  border: 1px solid var(--color-border);
  box-shadow: var(--shadow);
}

/* ── Icon button ──────────────────────────────────────────────────────── */

.btn-icon {
  min-width: 44px;
  min-height: 44px;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  font-size: 1.125rem;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0;
}

/* ── Category groups (menu) ───────────────────────────────────────────── */

#category-groups {
  margin-bottom: 24px;
}

.category-group {
  margin-bottom: 16px;
}

.category-group-label {
  font-size: 0.8rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--color-group-header);
  margin-bottom: 8px;
  padding-left: 4px;
}

.category-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
}

.mode-btn {
  padding: 14px 10px;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  font-size: 0.9rem;
  font-weight: 500;
  text-align: center;
  box-shadow: var(--shadow);
  line-height: 1.3;
}

.mode-btn:active {
  background: var(--color-primary);
  color: #fff;
  border-color: var(--color-primary);
}

.mode-btn .mode-icon {
  display: block;
  font-size: 1.3rem;
  margin-bottom: 4px;
}

.mode-btn small {
  font-size: 0.75rem;
  color: var(--color-text-secondary);
}

.mode-btn:active small {
  color: rgba(255,255,255,0.8);
}

/* Full-width for single category in a group (mixed) */
.category-grid--single {
  grid-template-columns: 1fr;
}

/* ── Options grid (training) ──────────────────────────────────────────── */

#options-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin: 16px 0;
}

.option-btn {
  min-height: 64px;
  padding: 16px 8px;
  background: var(--color-btn-bg);
  border: 2px solid var(--color-border);
  border-radius: var(--radius);
  font-size: clamp(1rem, 4.5vw, 1.35rem);
  font-weight: 600;
  text-align: center;
  box-shadow: var(--shadow);
  overflow-wrap: break-word;
  word-break: break-word;
  hyphens: none;
  line-height: 1.2;
}

.option-btn.long-text {
  font-size: clamp(0.85rem, 3.5vw, 1.1rem);
}

.option-btn.correct {
  background: var(--color-correct-bg);
  border-color: var(--color-correct);
  color: var(--color-correct);
}

.option-btn.wrong {
  background: var(--color-wrong-bg);
  border-color: var(--color-wrong);
  color: var(--color-wrong);
}

/* ── Training header ──────────────────────────────────────────────────── */

.training-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 12px;
  gap: 8px;
}

.btn-back {
  min-width: 44px;
  min-height: 44px;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  font-size: 1.125rem;
  color: var(--color-text-secondary);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0;
  flex-shrink: 0;
}

.category-indicator {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--color-text-secondary);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  flex-shrink: 1;
  min-width: 0;
}

#score-display {
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--color-text);
  flex-shrink: 0;
}

/* ── Replay button ────────────────────────────────────────────────────── */

.btn-replay {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 100%;
  padding: 20px;
  margin-bottom: 8px;
  background: var(--color-surface);
  border: 2px solid var(--color-primary);
  border-radius: var(--radius);
  font-size: 1.25rem;
  color: var(--color-primary);
  font-weight: 600;
  box-shadow: var(--shadow);
}

.btn-replay:active {
  background: var(--color-primary);
  color: #fff;
}

/* ── Action buttons row ───────────────────────────────────────────────── */

.action-row {
  display: flex;
  gap: 12px;
  margin-top: 8px;
}

.action-row button {
  flex: 1;
  padding: 14px 8px;
  font-size: 0.95rem;
  font-weight: 600;
}

.btn-skip {
  background: var(--color-surface);
  color: var(--color-text-secondary);
  border: 1px solid var(--color-border);
}

.btn-end {
  background: var(--color-surface);
  color: var(--color-wrong);
  border: 1px solid var(--color-border);
}

.btn-next {
  background: var(--color-primary);
  color: #fff;
}

/* ── Speed controls ───────────────────────────────────────────────────── */

.speed-control {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-top: 16px;
}

.speed-label {
  font-size: 0.85rem;
  color: var(--color-text-secondary);
  white-space: nowrap;
}

.speed-buttons {
  display: flex;
  gap: 4px;
  flex: 1;
}

.speed-btn {
  flex: 1;
  padding: 10px 4px;
  min-height: 44px;
  font-size: 0.85rem;
  font-weight: 500;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  color: var(--color-text-secondary);
}

.speed-btn.active {
  background: var(--color-speed-active);
  color: var(--color-speed-text);
  border-color: var(--color-speed-active);
}

/* ── Hidden utility ───────────────────────────────────────────────────── */

.hidden {
  display: none !important;
}

/* ── Onboarding ───────────────────────────────────────────────────────── */

.onboarding-content {
  flex: 1;
  display: flex;
  flex-direction: column;
  justify-content: center;
  text-align: center;
}

.onboarding-content .emoji-hero {
  font-size: 3rem;
  margin-bottom: 16px;
}

.onboarding-steps {
  text-align: left;
  margin: 20px 0;
  padding: 0 8px;
}

.onboarding-steps li {
  margin-bottom: 12px;
  padding-left: 8px;
  line-height: 1.4;
  color: var(--color-text);
  list-style: none;
}

.onboarding-steps li .step-icon {
  margin-right: 8px;
}

/* ── Summary ──────────────────────────────────────────────────────────── */

.summary-content {
  flex: 1;
  display: flex;
  flex-direction: column;
  justify-content: center;
  text-align: center;
}

.summary-score {
  font-size: 3rem;
  font-weight: 700;
  color: var(--color-primary);
  margin-bottom: 8px;
}

.summary-detail {
  font-size: 1.125rem;
  color: var(--color-text-secondary);
  margin-bottom: 6px;
}

.summary-actions {
  display: flex;
  flex-direction: column;
  gap: 12px;
  margin-top: 24px;
}

/* ── Error screen ─────────────────────────────────────────────────────── */

.error-content {
  flex: 1;
  display: flex;
  flex-direction: column;
  justify-content: center;
  text-align: center;
}

.error-content .emoji-hero {
  font-size: 3rem;
  margin-bottom: 16px;
}

#error-message {
  font-size: 1rem;
  line-height: 1.5;
  color: var(--color-text);
  margin-bottom: 24px;
}

/* ── Toast notification ───────────────────────────────────────────────── */

.toast {
  position: fixed;
  bottom: calc(20px + var(--safe-bottom));
  left: 16px;
  right: 16px;
  max-width: 400px;
  margin: 0 auto;
  padding: 12px 16px;
  background: var(--color-text);
  color: var(--color-bg);
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  text-align: center;
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.3s, transform 0.3s;
  pointer-events: none;
  z-index: 100;
}

.toast.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ── Language switchers ────────────────────────────────────────────────── */

.lang-switchers {
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin-bottom: 20px;
  padding: 12px;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
}

.lang-switcher {
  display: flex;
  align-items: center;
  gap: 8px;
}

.lang-label {
  font-size: 0.85rem;
  color: var(--color-text-secondary);
  white-space: nowrap;
  min-width: 80px;
}

.lang-buttons {
  display: flex;
  gap: 4px;
  flex: 1;
}

.lang-btn {
  flex: 1;
  padding: 8px 4px;
  min-height: 40px;
  font-size: 0.85rem;
  font-weight: 500;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  color: var(--color-text-secondary);
  cursor: pointer;
  transition: background-color 0.15s, border-color 0.15s;
}

.lang-btn.active {
  background: var(--color-speed-active);
  color: var(--color-speed-text);
  border-color: var(--color-speed-active);
}

.lang-btn:active {
  transform: scale(0.97);
}

/* ── Menu extras ──────────────────────────────────────────────────────── */

.menu-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 20px;
}

.menu-header h1 {
  margin-bottom: 0;
  text-align: left;
}

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

.btn-help {
  min-width: 44px;
  min-height: 44px;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  font-size: 1.125rem;
  color: var(--color-text-secondary);
  display: flex;
  align-items: center;
  justify-content: center;
}

/* ── Session length selector ───────────────────────────────────────────── */

.session-length-control {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-top: 12px;
}

.session-length-label {
  font-size: 0.85rem;
  color: var(--color-text-secondary);
  white-space: nowrap;
}

.session-length-buttons {
  display: flex;
  gap: 4px;
  flex: 1;
}

.session-length-btn {
  flex: 1;
  padding: 10px 4px;
  min-height: 44px;
  font-size: 0.85rem;
  font-weight: 500;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  color: var(--color-text-secondary);
}

.session-length-btn.active {
  background: var(--color-speed-active);
  color: var(--color-speed-text);
  border-color: var(--color-speed-active);
}

/* ── Summary category label ───────────────────────────────────────────── */

.summary-category {
  font-size: 1rem;
  color: var(--color-text-secondary);
  margin-bottom: 12px;
}

/* ── Responsive adjustments ───────────────────────────────────────────── */

@media (max-width: 374px) {
  .option-btn {
    font-size: 0.95rem;
    padding: 12px 6px;
    min-height: 56px;
  }

  .mode-btn {
    padding: 12px 6px;
    font-size: 0.8rem;
  }

  .mode-btn .mode-icon {
    font-size: 1.1rem;
  }
}

@media (min-width: 768px) {
  .screen {
    max-width: 480px;
  }
}