/* ══════════════════════════════════════════════════════════════════
   style.css — Math-Explore: Kid-friendly arithmetic learning app
   Playful, warm, colorful, mobile-friendly
   ══════════════════════════════════════════════════════════════════ */

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

:root {
  --clr-bg:         #FFF8F0;
  --clr-primary:    #FF6B6B;
  --clr-secondary:  #FFD93D;
  --clr-green:      #6BCB77;
  --clr-blue:       #4D96FF;
  --clr-purple:     #CC5DE8;
  --clr-orange:     #FF922B;
  --clr-text:       #2D2D2D;
  --clr-text-light: #666;
  --clr-card:       #FFFFFF;
  --clr-shadow:     rgba(0,0,0,0.10);
  --radius:         18px;
  --radius-sm:      10px;
  --font:           'Segoe UI', 'Helvetica Neue', Arial, sans-serif;
  --transition:     0.2s ease;
}

html, body {
  height: 100%;
  font-family: var(--font);
  background: var(--clr-bg);
  color: var(--clr-text);
  overflow-x: hidden;
  touch-action: manipulation;
  -webkit-tap-highlight-color: transparent;
}

/* ── Typography ──────────────────────────────────────────────────── */
h1 { font-size: clamp(2rem, 6vw, 3.5rem); font-weight: 900; }
h2 { font-size: clamp(1.4rem, 4vw, 2.2rem); font-weight: 800; }
h3 { font-size: clamp(1.1rem, 3vw, 1.6rem); font-weight: 700; }
p  { line-height: 1.5; }

/* ── Layout helpers ──────────────────────────────────────────────── */
.flex { display: flex; }
.flex-center { display: flex; align-items: center; justify-content: center; }
.flex-col { flex-direction: column; }
.gap-sm { gap: 8px; }
.gap-md { gap: 16px; }
.gap-lg { gap: 24px; }
.text-center { text-align: center; }

/* ══════════════════════════════════════════════════════════════════
   SCREENS — Only one visible at a time
   ══════════════════════════════════════════════════════════════════ */
.screen {
  display: none;
  min-height: 100vh;
  padding: 16px;
  animation: fadeIn 0.25s ease;
}
.screen.active { display: block; }

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(8px); }
  to   { opacity: 1; transform: translateY(0); }
}

/* ══════════════════════════════════════════════════════════════════
   HOME SCREEN
   ══════════════════════════════════════════════════════════════════ */
#home-screen {
  background: linear-gradient(160deg, #FFF4E0 0%, #FFF0F9 50%, #E8F4FF 100%);
}

.home-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 8px 0 16px;
}

.app-title {
  font-size: clamp(1.8rem, 5vw, 2.8rem);
  font-weight: 900;
  background: linear-gradient(135deg, var(--clr-primary), var(--clr-orange), var(--clr-secondary));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  filter: drop-shadow(0 2px 4px rgba(255,107,107,0.25));
}

.btn-parent {
  background: #f5f5f5;
  border: none;
  border-radius: 50%;
  width: 48px;
  height: 48px;
  font-size: 1.4rem;
  cursor: pointer;
  transition: var(--transition);
  display: flex;
  align-items: center;
  justify-content: center;
  user-select: none;
}
.btn-parent:hover { background: #e0e0e0; transform: scale(1.05); }

/* Stats bar */
.stats-bar {
  display: flex;
  gap: 10px;
  justify-content: center;
  flex-wrap: wrap;
  margin: 8px 0 20px;
}

.stat-chip {
  background: white;
  border-radius: 50px;
  padding: 8px 16px;
  font-size: 0.95rem;
  font-weight: 700;
  box-shadow: 0 2px 8px var(--clr-shadow);
  display: flex;
  align-items: center;
  gap: 6px;
  min-width: 80px;
  justify-content: center;
}
.stat-chip .stat-icon { font-size: 1.2rem; }

/* Level progress */
.level-progress-wrap {
  background: white;
  border-radius: var(--radius);
  padding: 12px 16px;
  margin-bottom: 20px;
  box-shadow: 0 2px 8px var(--clr-shadow);
}
.level-progress-label {
  display: flex;
  justify-content: space-between;
  font-weight: 700;
  font-size: 0.9rem;
  margin-bottom: 6px;
}
.progress-bar {
  height: 14px;
  background: #f0f0f0;
  border-radius: 50px;
  overflow: hidden;
}
.progress-fill {
  height: 100%;
  border-radius: 50px;
  background: linear-gradient(90deg, var(--clr-green), var(--clr-blue));
  transition: width 0.6s cubic-bezier(.22,1,.36,1);
}

/* Mode cards grid */
.mode-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 14px;
  max-width: 600px;
  margin: 0 auto;
}

@media (min-width: 600px) {
  .mode-grid { grid-template-columns: repeat(3, 1fr); }
}

.mode-card {
  background: var(--clr-card);
  border-radius: var(--radius);
  padding: 20px 12px 16px;
  text-align: center;
  cursor: pointer;
  border: 2.5px solid transparent;
  box-shadow: 0 3px 12px var(--clr-shadow);
  transition: transform 0.18s ease, box-shadow 0.18s ease;
  user-select: none;
  position: relative;
  overflow: hidden;
}
.mode-card:hover  { transform: translateY(-4px) scale(1.03); box-shadow: 0 8px 24px var(--clr-shadow); }
.mode-card:active { transform: scale(0.97); }

.mode-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 5px;
  border-radius: var(--radius) var(--radius) 0 0;
}

.mode-card[data-mode="numberRead"]::before   { background: var(--clr-primary); }
.mode-card[data-mode="counting"]::before     { background: var(--clr-green); }
.mode-card[data-mode="addition"]::before     { background: var(--clr-blue); }
.mode-card[data-mode="subtraction"]::before  { background: var(--clr-orange); }
.mode-card[data-mode="placeValue"]::before   { background: var(--clr-purple); }
.mode-card[data-mode="blocks3d"]::before     { background: var(--clr-secondary); }
.mode-card[data-mode="rewards"]::before      { background: linear-gradient(90deg, var(--clr-primary), var(--clr-secondary)); }

.mode-card-icon  { font-size: 2.5rem; margin-bottom: 8px; }
.mode-card-label { font-size: 1rem; font-weight: 800; color: var(--clr-text); }

/* Badges strip */
.badges-strip {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  justify-content: center;
  margin-top: 16px;
}
.badge-item {
  background: white;
  border-radius: 50px;
  padding: 6px 12px;
  font-size: 0.85rem;
  font-weight: 700;
  box-shadow: 0 2px 6px var(--clr-shadow);
  display: flex;
  align-items: center;
  gap: 4px;
}

/* ══════════════════════════════════════════════════════════════════
   QUIZ SCREENS (shared by all modes)
   ══════════════════════════════════════════════════════════════════ */
.quiz-screen {
  max-width: 640px;
  margin: 0 auto;
}

.quiz-header {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 16px;
}

.btn-back {
  background: white;
  border: none;
  border-radius: 50%;
  width: 44px;
  height: 44px;
  font-size: 1.3rem;
  cursor: pointer;
  box-shadow: 0 2px 8px var(--clr-shadow);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  transition: var(--transition);
}
.btn-back:hover { background: #f0f0f0; transform: scale(1.05); }

.quiz-title {
  flex: 1;
  font-size: 1.3rem;
  font-weight: 800;
}

.score-badge {
  background: var(--clr-secondary);
  border-radius: 50px;
  padding: 6px 14px;
  font-weight: 800;
  font-size: 0.95rem;
  white-space: nowrap;
}

/* Question card */
.question-card {
  background: white;
  border-radius: var(--radius);
  padding: 28px 20px;
  text-align: center;
  box-shadow: 0 4px 16px var(--clr-shadow);
  margin-bottom: 16px;
  min-height: 160px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 10px;
}

.question-number-big {
  font-size: clamp(3rem, 15vw, 6rem);
  font-weight: 900;
  color: var(--clr-primary);
  line-height: 1;
}

.question-words-big {
  font-size: clamp(1.4rem, 5vw, 2.6rem);
  font-weight: 800;
  color: var(--clr-blue);
  line-height: 1.2;
  text-align: center;
}

.question-instruction {
  font-size: 1rem;
  color: var(--clr-text-light);
  font-weight: 600;
}

/* Emoji display */
.emoji-grid {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  justify-content: center;
  max-width: 340px;
  margin: 0 auto;
}
.emoji-item {
  font-size: clamp(1.5rem, 5vw, 2.2rem);
  line-height: 1;
  transition: transform 0.15s ease;
  cursor: default;
  user-select: none;
}
.emoji-item.highlighted { transform: scale(1.4); filter: drop-shadow(0 0 6px gold); }
.emoji-item.dim         { opacity: 0.25; transform: scale(0.85); }

/* Addition/subtraction visual */
.add-visual {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
  justify-content: center;
}
.add-group {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
}
.add-group-num {
  font-size: 1.4rem;
  font-weight: 800;
  color: var(--clr-text);
}
.add-operator {
  font-size: 2rem;
  font-weight: 900;
  color: var(--clr-primary);
}

/* Math expression */
.math-expr {
  font-size: clamp(2rem, 8vw, 4.5rem);
  font-weight: 900;
  color: var(--clr-text);
  font-family: 'Courier New', monospace;
}
.math-expr span { color: var(--clr-primary); }

/* Answer choices */
.choices {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  margin-bottom: 12px;
}

.choice-btn {
  background: white;
  border: 3px solid #e0e0e0;
  border-radius: var(--radius);
  padding: 16px 8px;
  font-size: clamp(1.1rem, 4vw, 1.6rem);
  font-weight: 800;
  cursor: pointer;
  transition: transform 0.15s ease, border-color 0.15s ease, background 0.15s ease;
  min-height: 64px;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  user-select: none;
  -webkit-tap-highlight-color: transparent;
}
.choice-btn:hover  { transform: scale(1.06); border-color: var(--clr-blue); }
.choice-btn:active { transform: scale(0.95); }
.choice-btn.correct {
  background: var(--clr-green);
  border-color: var(--clr-green);
  color: white;
  animation: popIn 0.3s cubic-bezier(.18,.89,.32,1.28);
}
.choice-btn.wrong {
  background: var(--clr-primary);
  border-color: var(--clr-primary);
  color: white;
  animation: shake 0.4s ease;
}
.choice-btn.disabled { pointer-events: none; opacity: 0.6; }

@keyframes popIn {
  0%   { transform: scale(0.9); }
  60%  { transform: scale(1.12); }
  100% { transform: scale(1); }
}

@keyframes shake {
  0%, 100% { transform: translateX(0); }
  20%       { transform: translateX(-7px); }
  40%       { transform: translateX(7px); }
  60%       { transform: translateX(-5px); }
  80%       { transform: translateX(4px); }
}

/* Feedback message */
.feedback-msg {
  text-align: center;
  font-size: 1.4rem;
  font-weight: 800;
  min-height: 44px;
  padding: 6px;
  border-radius: var(--radius-sm);
  transition: all 0.2s;
}
.feedback-msg.correct-msg { color: var(--clr-green); }
.feedback-msg.wrong-msg   { color: var(--clr-primary); }

/* Points earned popup */
.points-popup {
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%) scale(0);
  background: var(--clr-secondary);
  border-radius: var(--radius);
  padding: 14px 28px;
  font-size: 1.8rem;
  font-weight: 900;
  box-shadow: 0 8px 30px rgba(255,217,61,0.5);
  z-index: 200;
  animation: pointsAnim 1s cubic-bezier(.18,.89,.32,1.28) forwards;
  pointer-events: none;
}
@keyframes pointsAnim {
  0%   { transform: translate(-50%, -50%) scale(0) translateY(0); opacity: 1; }
  30%  { transform: translate(-50%, -60%) scale(1.1); opacity: 1; }
  70%  { transform: translate(-50%, -80%) scale(1); opacity: 1; }
  100% { transform: translate(-50%, -110%) scale(0.9); opacity: 0; }
}

/* Streak display */
.streak-display {
  text-align: center;
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--clr-orange);
  min-height: 24px;
}

/* Next button */
.btn-next {
  display: none;
  width: 100%;
  padding: 16px;
  background: linear-gradient(135deg, var(--clr-blue), var(--clr-purple));
  color: white;
  border: none;
  border-radius: var(--radius);
  font-size: 1.2rem;
  font-weight: 800;
  cursor: pointer;
  margin-top: 8px;
  transition: var(--transition);
  box-shadow: 0 4px 14px rgba(77,150,255,0.35);
}
.btn-next:hover  { transform: translateY(-2px); box-shadow: 0 6px 18px rgba(77,150,255,0.45); }
.btn-next:active { transform: scale(0.98); }
.btn-next.show   { display: block; animation: slideUp 0.25s ease; }

@keyframes slideUp {
  from { opacity: 0; transform: translateY(12px); }
  to   { opacity: 1; transform: translateY(0); }
}

/* Helper button (show blocks, count one-by-one) */
.btn-helper {
  background: var(--clr-secondary);
  border: none;
  border-radius: 50px;
  padding: 10px 20px;
  font-size: 0.95rem;
  font-weight: 700;
  cursor: pointer;
  transition: var(--transition);
  margin-top: 8px;
  display: inline-flex;
  align-items: center;
  gap: 6px;
}
.btn-helper:hover { background: #ffc800; transform: scale(1.03); }

/* ══════════════════════════════════════════════════════════════════
   PLACE VALUE SCREEN
   ══════════════════════════════════════════════════════════════════ */
.place-value-visual {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  justify-content: center;
  margin: 12px 0;
}

.place-column {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  min-width: 60px;
}
.place-column.target-col .place-digit {
  background: var(--clr-secondary);
  border: 3px solid var(--clr-orange);
  box-shadow: 0 0 0 4px rgba(255,217,61,0.4);
}
.place-label {
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--clr-text-light);
  text-align: center;
}
.place-digit {
  width: 52px;
  height: 52px;
  background: var(--clr-blue);
  color: white;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.6rem;
  font-weight: 900;
  box-shadow: 0 3px 8px var(--clr-shadow);
}

/* Block icons for place value */
.pv-blocks {
  display: flex;
  flex-wrap: wrap;
  gap: 3px;
  justify-content: center;
  max-width: 120px;
}
.pv-block-cube  { font-size: 0.9rem; }
.pv-block-rod   { font-size: 1.1rem; }
.pv-block-flat  { font-size: 1.3rem; }

/* ══════════════════════════════════════════════════════════════════
   3D BLOCK SCREEN
   ══════════════════════════════════════════════════════════════════ */

/* Outer card: clips any overflow in 2D, provides visual boundary.
   IMPORTANT: do NOT put perspective here — WebKit/Safari flattens
   3D children when overflow:hidden and perspective are on the same
   element. Perspective lives on .b3d-stage instead. */
.blocks3d-container {
  width: 100%;
  height: 320px;
  background: linear-gradient(135deg, #E8F4FF, #FFF0F5);
  border-radius: var(--radius);
  overflow: hidden;
  position: relative;
  margin-bottom: 12px;
  cursor: grab;
  box-shadow: 0 4px 16px var(--clr-shadow);
  user-select: none;
  -webkit-user-select: none;
  touch-action: none;
}
.blocks3d-container:active { cursor: grabbing; }

/* Stage: fills the container; provides perspective.
   No overflow:hidden here — see comment above. */
.b3d-stage {
  position: absolute;
  inset: 0;
  perspective: 900px;
  -webkit-perspective: 900px;
  perspective-origin: 50% 45%;
  display: flex;
  align-items: center;
  justify-content: center;
}

/* Scene: receives the rotateX/rotateY drag transform.
   Must use preserve-3d so children are rendered in 3D. */
.b3d-scene {
  transform-style: preserve-3d;
  -webkit-transform-style: preserve-3d;
  will-change: transform;
  position: relative;
  width: 0;
  height: 0;
}

/* Model: zero-size anchor. Cubes are absolutely positioned around
   its origin using translate3d, so the structure is auto-centred. */
.b3d-model {
  position: relative;
  width: 0;
  height: 0;
  transform-style: preserve-3d;
  -webkit-transform-style: preserve-3d;
}

.blocks3d-controls {
  display: flex;
  gap: 10px;
  justify-content: center;
  margin-bottom: 12px;
}
.btn-3d-ctrl {
  background: white;
  border: 2px solid #e0e0e0;
  border-radius: 50px;
  padding: 8px 16px;
  font-size: 0.9rem;
  font-weight: 700;
  cursor: pointer;
  transition: var(--transition);
  display: flex;
  align-items: center;
  gap: 6px;
}
.btn-3d-ctrl:hover { background: #f5f5f5; border-color: var(--clr-blue); }

/* ══════════════════════════════════════════════════════════════════
   REWARDS / LEVEL SCREEN
   ══════════════════════════════════════════════════════════════════ */
#rewards-screen {
  background: linear-gradient(160deg, #FFF4E0, #F9F0FF);
}

.rewards-header {
  text-align: center;
  margin-bottom: 20px;
}

.big-level-display {
  font-size: clamp(4rem, 18vw, 8rem);
  font-weight: 900;
  line-height: 1;
  background: linear-gradient(135deg, var(--clr-primary), var(--clr-orange));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.rewards-stats-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 12px;
  max-width: 400px;
  margin: 0 auto 20px;
}
.rewards-stat {
  background: white;
  border-radius: var(--radius);
  padding: 16px 12px;
  text-align: center;
  box-shadow: 0 2px 8px var(--clr-shadow);
}
.rewards-stat .rs-val {
  font-size: 2rem;
  font-weight: 900;
  color: var(--clr-primary);
  line-height: 1;
}
.rewards-stat .rs-label {
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--clr-text-light);
  margin-top: 4px;
}

.badges-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  max-width: 400px;
  margin: 0 auto;
}
@media (min-width: 480px) {
  .badges-grid { grid-template-columns: repeat(4, 1fr); }
}

.badge-card {
  background: white;
  border-radius: var(--radius);
  padding: 14px 8px;
  text-align: center;
  box-shadow: 0 2px 8px var(--clr-shadow);
  position: relative;
}
.badge-card.locked { opacity: 0.35; filter: grayscale(0.8); }
.badge-card .badge-icon { font-size: 2rem; }
.badge-card .badge-name { font-size: 0.7rem; font-weight: 700; color: var(--clr-text-light); margin-top: 4px; }

/* ══════════════════════════════════════════════════════════════════
   PARENT / SETTINGS MODAL
   ══════════════════════════════════════════════════════════════════ */
.modal-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.5);
  z-index: 300;
  align-items: center;
  justify-content: center;
  padding: 16px;
  animation: fadeIn 0.2s ease;
}
.modal-overlay.open { display: flex; }

.modal-box {
  background: white;
  border-radius: var(--radius);
  padding: 28px 24px;
  max-width: 480px;
  width: 100%;
  max-height: 90vh;
  overflow-y: auto;
  box-shadow: 0 12px 40px rgba(0,0,0,0.2);
  animation: popIn 0.3s cubic-bezier(.18,.89,.32,1.28);
}

.modal-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 20px;
}
.btn-close-modal {
  background: #f0f0f0;
  border: none;
  border-radius: 50%;
  width: 38px;
  height: 38px;
  font-size: 1.1rem;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
}
.btn-close-modal:hover { background: #e0e0e0; }

/* Settings rows */
.setting-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 0;
  border-bottom: 1px solid #f0f0f0;
  gap: 12px;
}
.setting-row:last-child { border-bottom: none; }
.setting-label {
  font-size: 1rem;
  font-weight: 700;
}
.setting-desc {
  font-size: 0.8rem;
  color: var(--clr-text-light);
}

/* Toggle switch */
.toggle {
  position: relative;
  width: 52px;
  height: 28px;
  flex-shrink: 0;
}
.toggle input { opacity: 0; width: 0; height: 0; }
.toggle-slider {
  position: absolute;
  inset: 0;
  background: #ccc;
  border-radius: 50px;
  cursor: pointer;
  transition: 0.3s;
}
.toggle-slider::before {
  content: '';
  position: absolute;
  width: 22px;
  height: 22px;
  left: 3px;
  top: 3px;
  background: white;
  border-radius: 50%;
  transition: 0.3s;
  box-shadow: 0 2px 4px rgba(0,0,0,0.2);
}
.toggle input:checked + .toggle-slider { background: var(--clr-green); }
.toggle input:checked + .toggle-slider::before { transform: translateX(24px); }

/* Big action buttons in modals */
.btn-action {
  width: 100%;
  padding: 14px;
  border: none;
  border-radius: var(--radius);
  font-size: 1rem;
  font-weight: 800;
  cursor: pointer;
  margin-top: 10px;
  transition: var(--transition);
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
}
.btn-action:hover  { filter: brightness(1.06); transform: translateY(-1px); }
.btn-action:active { transform: scale(0.98); }
.btn-action.primary   { background: var(--clr-blue); color: white; }
.btn-action.danger    { background: var(--clr-primary); color: white; }
.btn-action.secondary { background: #f0f0f0; color: var(--clr-text); }

/* Parent gate */
.parent-gate {
  text-align: center;
  padding: 20px 0;
}
.gate-hold-btn {
  width: 120px;
  height: 120px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--clr-blue), var(--clr-purple));
  border: none;
  color: white;
  font-size: 1rem;
  font-weight: 800;
  cursor: pointer;
  position: relative;
  overflow: hidden;
  box-shadow: 0 6px 20px rgba(77,150,255,0.4);
  user-select: none;
  -webkit-tap-highlight-color: transparent;
}
.gate-hold-progress {
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  height: 0%;
  background: rgba(255,255,255,0.3);
  transition: none;
}
.gate-instruction {
  margin-top: 12px;
  font-weight: 700;
  color: var(--clr-text-light);
}

/* Level-up celebration overlay */
.levelup-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.6);
  z-index: 400;
  align-items: center;
  justify-content: center;
  animation: fadeIn 0.2s ease;
}
.levelup-overlay.show { display: flex; }
.levelup-box {
  background: white;
  border-radius: var(--radius);
  padding: 40px 30px;
  text-align: center;
  box-shadow: 0 16px 50px rgba(0,0,0,0.25);
  animation: popIn 0.4s cubic-bezier(.18,.89,.32,1.28);
  max-width: 320px;
  width: 90%;
}
.levelup-emoji { font-size: 4.5rem; margin-bottom: 10px; }
.levelup-title { font-size: 2rem; font-weight: 900; color: var(--clr-primary); }
.levelup-sub   { font-size: 1rem; color: var(--clr-text-light); margin: 6px 0 16px; }

/* ══════════════════════════════════════════════════════════════════
   BIG NUMBER DEMO (parent mode)
   ══════════════════════════════════════════════════════════════════ */
.bignum-demo {
  background: #1a1a2e;
  color: #eee;
  border-radius: var(--radius);
  padding: 20px;
  font-family: 'Courier New', monospace;
}
.bignum-display {
  font-size: clamp(0.8rem, 2.5vw, 1.1rem);
  word-break: break-all;
  color: var(--clr-secondary);
  margin: 8px 0;
}
.bignum-label {
  font-size: 0.8rem;
  color: #888;
  margin-top: 6px;
}

/* ══════════════════════════════════════════════════════════════════
   CONFETTI
   ══════════════════════════════════════════════════════════════════ */
.confetti-container {
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 500;
  overflow: hidden;
}
.confetti-piece {
  position: absolute;
  top: -10px;
  animation: confettiFall linear forwards;
}
@keyframes confettiFall {
  0%   { transform: translateY(0) rotate(0deg); opacity: 1; }
  100% { transform: translateY(110vh) rotate(720deg); opacity: 0; }
}

/* ══════════════════════════════════════════════════════════════════
   UTILITY CLASSES
   ══════════════════════════════════════════════════════════════════ */
.hidden { display: none !important; }
.mt-sm  { margin-top: 8px; }
.mt-md  { margin-top: 16px; }
.mt-lg  { margin-top: 24px; }
.mb-sm  { margin-bottom: 8px; }
.mb-md  { margin-bottom: 16px; }

/* ── Difficulty select ─────────────────────────────────────────── */
select.setting-select {
  padding: 8px 12px;
  border-radius: var(--radius-sm);
  border: 2px solid #e0e0e0;
  font-size: 0.9rem;
  font-weight: 700;
  background: white;
  cursor: pointer;
  max-width: 140px;
}

/* ── Scrollbar styling ─────────────────────────────────────────── */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: #ccc; border-radius: 3px; }

/* ── No-animation mode ─────────────────────────────────────────── */
body.no-anim *, body.no-anim *::before, body.no-anim *::after {
  animation-duration: 0.001ms !important;
  transition-duration: 0.001ms !important;
}

/* ── Responsive tweaks ─────────────────────────────────────────── */
@media (max-width: 380px) {
  .choices { grid-template-columns: repeat(3, 1fr); gap: 8px; }
  .choice-btn { font-size: 1rem; padding: 12px 4px; min-height: 54px; }
  .mode-grid { gap: 10px; }
  .mode-card { padding: 14px 8px 12px; }
  .mode-card-icon { font-size: 2rem; }
}

/* ── Developer contact footer ──────────────────────────────────── */
.dev-footer {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: center;
  gap: 6px;
  margin-top: 24px;
  padding: 10px 0 4px;
  border-top: 1px solid rgba(0,0,0,0.07);
  font-size: 0.75rem;
  color: var(--clr-text-light);
}
.dev-footer-link {
  color: var(--clr-text-light);
  text-decoration: underline;
  text-underline-offset: 2px;
  transition: color var(--transition);
}
.dev-footer-link:hover { color: var(--clr-text); }
.dev-footer-sep { opacity: 0.5; }

/* ══════════════════════════════════════════════════════════════════════════
   AD BANNER
   The banner is injected into the active module screen by ad-manager.js.
   It is never added to the home screen or the rewards screen.
   Height is reserved in advance to prevent layout shift; content fades in
   after the 60-second delay.
══════════════════════════════════════════════════════════════════════════ */

/* Wrapper: fixed bar at the very bottom of the viewport so it never
   overlaps the interactive content above it. */
#module-ad-wrap {
  position: fixed;
  bottom: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 100%;
  max-width: 728px;
  /* Reserve space before ad appears to avoid layout shift */
  min-height: 60px;
  box-sizing: border-box;
  background: #fff;
  border-top: 1px solid #eee;
  z-index: 900;
  /* Starts transparent; fades to full opacity when the ad is ready */
  opacity: 0;
  transition: opacity 0.5s ease;
  /* Ensure the banner never intercepts taps before the ad is ready */
  pointer-events: none;
}

#module-ad-wrap.ad-visible {
  opacity: 1;
  pointer-events: auto;
}

/* ── Placeholder ─────────────────────────────────────────────────────────
   Shown when ADS_ENABLED is false.  Visually reserves the same space a
   real banner ad would use.  Kept subtle and child-friendly. */
.ad-placeholder {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 60px;
  background: #f0f0f0;
  border: 1px dashed #ccc;
  border-radius: 8px;
  color: #bbb;
  font-size: 0.78rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  user-select: none;
}

/* ── Make quiz screens scroll past the ad without overlap ────────────────
   Extra bottom padding so the Next button / choices are never hidden
   behind the fixed ad banner (60px height + 16px gap). */
body.ad-visible .quiz-screen {
  padding-bottom: 76px;
}

/* ── Responsive ──────────────────────────────────────────────────────────
   On small phones the banner spans full width; on tablets/desktops it is
   capped at 728px (standard leaderboard width). */
@media (max-width: 600px) {
  #module-ad-wrap {
    max-width: 100%;
  }
}