:root{
  color-scheme: light dark;
  --bg: #f8fafc;
  --bg-alt: #ffffff;
  --text: #0f172a;
  --muted: #475569;
  --primary: #2563eb;
  --primary-dark: #1d4ed8;
  --accent: #7c3aed;
  --success: #16a34a;
  --danger: #ef4444;
  --border: #e2e8f0;
  --shadow: 0 10px 24px rgba(15, 23, 42, 0.12);
  --radius-lg: 18px;
  --radius-md: 12px;
  --radius-sm: 8px;
  --space-1: 6px;
  --space-2: 10px;
  --space-3: 14px;
  --space-4: 18px;
  --space-5: 24px;
  --space-6: 32px;
  --space-7: 40px;
  --max-width: 1100px;
}

@media (prefers-color-scheme: dark){
  :root{
    --bg: #0b1220;
    --bg-alt: #111827;
    --text: #f8fafc;
    --muted: #cbd5f5;
    --primary: #60a5fa;
    --primary-dark: #3b82f6;
    --accent: #c084fc;
    --border: #1f2937;
    --shadow: 0 12px 30px rgba(15, 23, 42, 0.5);
  }
}

*{ box-sizing: border-box; }
body{
  margin: 0;
  font-family: "Nunito", system-ui, sans-serif;
  background: var(--bg);
  color: var(--text);
}

main{
  padding: var(--space-6) var(--space-4) var(--space-7);
}

.container{
  max-width: var(--max-width);
  margin: 0 auto;
}

.eyebrow{
  font: 700 12px/1 "Poppins", sans-serif;
  text-transform: uppercase;
  letter-spacing: .2em;
  color: var(--accent);
}

.page-hero{
  text-align: center;
  padding: var(--space-6) var(--space-4) var(--space-5);
}

.page-hero h1{
  font: 700 36px/1.1 "Poppins", sans-serif;
  margin: var(--space-2) 0 var(--space-2);
}

.page-hero p{
  margin: 0 auto var(--space-4);
  max-width: 760px;
  color: var(--muted);
  font-size: 18px;
}

.hero-actions{
  display: flex;
  gap: var(--space-2);
  justify-content: center;
  flex-wrap: wrap;
}

.btn{
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 12px 18px;
  border-radius: var(--radius-md);
  border: 1px solid var(--primary);
  background: var(--primary);
  color: #fff;
  font: 700 14px/1 "Poppins", sans-serif;
  text-decoration: none;
  transition: transform .15s ease, box-shadow .15s ease, background .15s ease;
}

.btn.secondary{
  background: transparent;
  color: var(--text);
  border-color: var(--border);
}

.btn:focus-visible,
.mode-card:focus-visible,
.tile:focus-visible,
select:focus-visible,
.toggle input:focus-visible{
  outline: 3px solid rgba(37, 99, 235, 0.45);
  outline-offset: 2px;
}

.btn:hover{ transform: translateY(-1px); box-shadow: var(--shadow); }

.section{
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: var(--space-5);
  margin-top: var(--space-5);
  box-shadow: var(--shadow);
}

.section h2{
  margin: 0 0 var(--space-3);
  font: 700 22px/1.2 "Poppins", sans-serif;
}

.section ul{
  margin: 0;
  padding-left: 18px;
  color: var(--muted);
}

.section li{ margin-bottom: 8px; }

.mode-grid{
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(210px, 1fr));
  gap: var(--space-4);
  margin-top: var(--space-4);
}

.mode-card{
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
  padding: var(--space-4);
  border-radius: var(--radius-md);
  border: 1px solid var(--border);
  background: linear-gradient(135deg, rgba(37, 99, 235, 0.08), transparent);
  text-decoration: none;
  color: inherit;
  min-height: 160px;
  transition: transform .15s ease, box-shadow .15s ease;
}

.mode-card:hover{ transform: translateY(-2px); box-shadow: var(--shadow); }

.mode-card span{
  font: 700 12px/1 "Poppins", sans-serif;
  text-transform: uppercase;
  letter-spacing: .16em;
  color: var(--accent);
}

.mode-card h3{
  margin: 0;
  font: 700 18px/1.2 "Poppins", sans-serif;
}

.mode-card p{
  margin: 0;
  color: var(--muted);
  font-size: 14px;
}

.ad-slot{
  margin: var(--space-5) 0;
  padding: var(--space-4);
  border: 1px dashed var(--border);
  border-radius: var(--radius-md);
  text-align: center;
  color: var(--muted);
  font: 700 12px/1 "Poppins", sans-serif;
  text-transform: uppercase;
  letter-spacing: .12em;
}

.faq details{
  border-top: 1px solid var(--border);
  padding: var(--space-3) 0;
}

.faq details:first-of-type{ border-top: none; }

.faq summary{
  cursor: pointer;
  font: 700 14px/1.4 "Poppins", sans-serif;
}

.faq p{ margin: var(--space-2) 0 0; color: var(--muted); }

.footer{
  text-align: center;
  padding: var(--space-4);
  color: var(--muted);
  font-size: 14px;
}

/* Game page */
.game-header{
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
  align-items: center;
  text-align: center;
}

.game-header h1{ margin: 0; font: 700 30px/1.1 "Poppins", sans-serif; }

.game-layout{
  display: grid;
  gap: var(--space-4);
  margin-top: var(--space-5);
}

.controls{
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-3);
  justify-content: space-between;
  align-items: center;
}

.controls .group{
  display: flex;
  gap: var(--space-2);
  flex-wrap: wrap;
  align-items: center;
}

select{
  padding: 10px 12px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  background: var(--bg-alt);
  color: var(--text);
  font-weight: 600;
}

.stats-bar{
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: var(--space-3);
}

.stat-card{
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: var(--space-3);
  text-align: center;
}

.stat-card span{
  display: block;
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: .12em;
  color: var(--muted);
}

.stat-card strong{
  font: 700 20px/1.2 "Poppins", sans-serif;
  margin-top: 4px;
  display: block;
}

.tile-grid{
  display: grid;
  gap: var(--space-3);
  grid-template-columns: repeat(auto-fit, minmax(90px, 1fr));
}

.tile{
  border: 2px solid transparent;
  border-radius: var(--radius-md);
  background: var(--bg-alt);
  padding: var(--space-4);
  min-height: 54px;
  display: flex;
  align-items: center;
  justify-content: center;
  font: 700 20px/1 "Poppins", sans-serif;
  cursor: pointer;
  transition: transform .12s ease, border-color .12s ease;
}

.tile[data-variant="color"]{
  color: #0f172a;
}

.tile:hover{ transform: translateY(-2px); border-color: rgba(37,99,235,.5); }

.tile.correct{
  animation: pulse .45s ease;
  border-color: var(--success);
}

.tile.wrong{
  animation: shake .3s ease;
  border-color: var(--danger);
}

@keyframes pulse{
  0%{ transform: scale(1); box-shadow: none; }
  60%{ transform: scale(1.05); box-shadow: 0 0 0 6px rgba(22,163,74,.15); }
  100%{ transform: scale(1); }
}

@keyframes shake{
  0%{ transform: translateX(0); }
  30%{ transform: translateX(-4px); }
  60%{ transform: translateX(4px); }
  100%{ transform: translateX(0); }
}

@media (prefers-reduced-motion: reduce){
  .tile.correct,
  .tile.wrong{ animation: none; }
}

.shape{
  width: 36px;
  height: 36px;
  display: inline-block;
}

.shape.circle{ border-radius: 50%; background: #22c55e; }
.shape.square{ background: #f97316; }
.shape.triangle{
  width: 0;
  height: 0;
  border-left: 18px solid transparent;
  border-right: 18px solid transparent;
  border-bottom: 32px solid #3b82f6;
}

.arrow{
  font-size: 30px;
  display: inline-block;
  transition: transform .2s ease;
}

.explanation{
  padding: var(--space-3);
  border-radius: var(--radius-md);
  border: 1px dashed var(--border);
  color: var(--muted);
  background: rgba(37,99,235,.08);
}

.toggle{
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
}

.toggle input{
  width: 42px;
  height: 22px;
  appearance: none;
  background: #cbd5f5;
  border-radius: 999px;
  position: relative;
  cursor: pointer;
  transition: background .2s ease;
}

.toggle input::after{
  content: "";
  position: absolute;
  width: 18px;
  height: 18px;
  top: 2px;
  left: 2px;
  border-radius: 50%;
  background: #fff;
  transition: transform .2s ease;
}

.toggle input:checked{ background: #22c55e; }
.toggle input:checked::after{ transform: translateX(20px); }

.modal{
  position: fixed;
  inset: 0;
  background: rgba(15, 23, 42, 0.6);
  display: none;
  align-items: center;
  justify-content: center;
  padding: var(--space-4);
  z-index: 9998;
}

.modal.open{ display: flex; }

.modal-card{
  background: var(--bg-alt);
  border-radius: var(--radius-lg);
  padding: var(--space-5);
  max-width: 420px;
  width: 100%;
  border: 1px solid var(--border);
  text-align: center;
}

.modal-card h2{ margin-top: 0; }

.modal-actions{
  display: grid;
  gap: var(--space-2);
  margin-top: var(--space-4);
}

.helper-text{
  color: var(--muted);
  font-size: 14px;
  line-height: 1.6;
}

@media (min-width: 860px){
  .game-layout{ grid-template-columns: 1fr; }
}

@media (max-width: 640px){
  .page-hero h1{ font-size: 30px; }
  .tile{ font-size: 18px; }
}