:root {
  --ink: #0b1221;
  --ink-muted: #1d2c3b;
  --bg: #071018;
  --panel: rgba(11, 18, 33, 0.82);
  --accent: #ef4444;
  --accent-soft: #fcd34d;
  --pine: #22c55e;
  --border: rgba(255, 255, 255, 0.08);
  --glow: 0 0 28px rgba(239, 68, 68, 0.45);
  --radius: 18px;
  --font: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
}

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

body.page {
  font-family: var(--font);
  color: #e5e7eb;
  background: radial-gradient(circle at 15% 20%, rgba(252, 211, 77, 0.12), transparent 25%),
    radial-gradient(circle at 85% 5%, rgba(34, 197, 94, 0.12), transparent 32%),
    radial-gradient(circle at 50% 80%, rgba(239, 68, 68, 0.16), transparent 35%),
    var(--bg);
  min-height: 100vh;
  line-height: 1.6;
  padding: 0 1rem 3rem;
  position: relative;
}

body.page::before,
body.page::after {
  content: '';
  position: fixed;
  inset: 0;
  pointer-events: none;
  background-image: radial-gradient(1px 1px at 10% 20%, rgba(255, 255, 255, 0.35), transparent),
    radial-gradient(1.5px 1.5px at 30% 80%, rgba(255, 255, 255, 0.28), transparent),
    radial-gradient(1px 1px at 70% 50%, rgba(255, 255, 255, 0.45), transparent),
    radial-gradient(1.2px 1.2px at 90% 30%, rgba(255, 255, 255, 0.3), transparent);
  animation: snowfall 14s linear infinite;
  opacity: 0.75;
}

body.page::after {
  animation-duration: 18s;
  filter: blur(1px);
}

.hero {
  padding: 3rem 0 1rem;
}

.hero__content {
  max-width: 780px;
  margin: 0 auto;
  text-align: center;
}

.hero h1 {
  font-size: clamp(2.5rem, 4vw, 3.5rem);
  color: #f8fafc;
  margin-bottom: 0.5rem;
  text-shadow: 0 12px 42px rgba(0, 0, 0, 0.35), var(--glow);
}

.eyebrow {
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: #cbd5e1;
  font-weight: 600;
  margin-bottom: 0.5rem;
}

.lede {
  color: #cbd5e1;
  margin: 0.35rem auto;
  max-width: 640px;
}

.content {
  max-width: 860px;
  margin: 0 auto;
  display: grid;
  gap: 1.5rem;
}

.card {
  background: linear-gradient(145deg, rgba(255, 255, 255, 0.04), rgba(17, 24, 39, 0.7));
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
  box-shadow: 0 30px 50px rgba(0, 0, 0, 0.35);
  backdrop-filter: blur(6px);
  position: relative;
  overflow: hidden;
}

.card h2 {
  margin-bottom: 0.75rem;
  color: #f8fafc;
}

.rules {
  display: grid;
  gap: 0.75rem;
  list-style-position: inside;
}

.hint {
  color: var(--accent-soft);
  font-style: italic;
}

.footer {
  max-width: 860px;
  margin: 2rem auto 0;
  text-align: center;
  color: #94a3b8;
  font-size: 0.9rem;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.75rem 1.2rem;
  border-radius: 12px;
  background: linear-gradient(135deg, var(--accent), var(--accent-soft));
  color: #0b1221;
  font-weight: 700;
  border: none;
  cursor: pointer;
  transition: transform 120ms ease, box-shadow 120ms ease;
  box-shadow: var(--glow);
}

.btn:disabled {
  opacity: 0.55;
  cursor: not-allowed;
  box-shadow: none;
}

.btn:hover:not(:disabled) {
  transform: translateY(-2px) scale(1.01);
}

.section-title {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  color: #f8fafc;
}

.section-title span {
  display: inline-flex;
  height: 10px;
  width: 10px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--accent), var(--pine));
  box-shadow: var(--glow);
}

.grid {
  display: grid;
  gap: 0.5rem;
}

.puzzle-grid {
  grid-template-columns: repeat(4, 1fr);
  grid-template-rows: repeat(4, 1fr);
  width: min(420px, 90vw);
  margin: 1rem auto;
}

.tile {
  aspect-ratio: 1 / 1;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 1.4rem;
  border-radius: 14px;
  background: linear-gradient(135deg, rgba(255, 255, 255, 0.08), rgba(255, 255, 255, 0.03));
  border: 1px solid rgba(255, 255, 255, 0.08);
  color: #f8fafc;
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.1);
  cursor: pointer;
  transition: transform 100ms ease, background 120ms ease, box-shadow 120ms ease;
}

.tile:hover {
  transform: translateY(-1px);
  background: linear-gradient(135deg, rgba(249, 115, 22, 0.2), rgba(255, 255, 255, 0.08));
  box-shadow: var(--glow);
}

.tile.empty {
  background: transparent;
  border: 1px dashed rgba(255, 255, 255, 0.08);
  cursor: default;
  box-shadow: none;
}

.status {
  text-align: center;
  color: #cbd5e1;
}

.alert {
  margin: 1rem auto 0;
  max-width: 480px;
  padding: 1rem;
  border-radius: 12px;
  background: rgba(34, 197, 94, 0.12);
  color: #bbf7d0;
  border: 1px solid rgba(34, 197, 94, 0.35);
}

.kana-grid {
  grid-template-columns: repeat(auto-fit, minmax(90px, 1fr));
  gap: 0.75rem;
}

.kana-card {
  background: linear-gradient(135deg, rgba(255, 255, 255, 0.06), rgba(255, 255, 255, 0.02));
  border-radius: 14px;
  border: 1px solid rgba(255, 255, 255, 0.08);
  padding: 1rem;
  text-align: center;
  cursor: pointer;
  transition: transform 120ms ease, box-shadow 120ms ease;
}

.kana-card:hover {
  transform: translateY(-1px) scale(1.01);
  box-shadow: var(--glow);
}

.kana-card .kana {
  font-size: 2rem;
  display: block;
  margin-bottom: 0.35rem;
}

.kana-card .romanji {
  color: #cbd5e1;
}

.badge {
  display: inline-flex;
  padding: 0.35rem 0.55rem;
  border-radius: 999px;
  border: 1px solid rgba(255, 255, 255, 0.1);
  background: rgba(255, 255, 255, 0.06);
  color: #cbd5e1;
  font-size: 0.85rem;
  gap: 0.25rem;
  align-items: center;
}

.quiz-card {
  background: linear-gradient(135deg, rgba(34, 197, 94, 0.08), rgba(239, 68, 68, 0.1));
}

.quiz-item {
  display: grid;
  gap: 0.5rem;
}

.quiz-item img {
  width: 100%;
  height: auto;
  border-radius: 12px;
  border: 1px solid rgba(255, 255, 255, 0.08);
}

.quiz-controls {
  display: flex;
  gap: 0.5rem;
  flex-wrap: wrap;
}

input[type="text"], textarea {
  width: 100%;
  padding: 0.75rem 0.85rem;
  border-radius: 12px;
  border: 1px solid rgba(255, 255, 255, 0.08);
  background: rgba(255, 255, 255, 0.05);
  color: #f8fafc;
  font-size: 1rem;
}

.quiz-status {
  color: #cbd5e1;
}

.progress {
  height: 10px;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.1);
  overflow: hidden;
}

.progress > div {
  height: 100%;
  width: 0;
  background: linear-gradient(135deg, var(--accent), var(--pine));
  transition: width 160ms ease;
}

.btn--frost {
  background: linear-gradient(135deg, #fff7ed, #e0f2fe);
  color: #0b1221;
  box-shadow: 0 10px 40px rgba(255, 255, 255, 0.35);
}

.audio-button {
  background: linear-gradient(135deg, rgba(255, 255, 255, 0.08), rgba(255, 255, 255, 0.02));
  border: 1px solid rgba(255, 255, 255, 0.08);
  border-radius: 12px;
  padding: 0.75rem 1rem;
  color: #f8fafc;
  display: inline-flex;
  gap: 0.65rem;
  align-items: center;
}

.audio-button span {
  background: rgba(239, 68, 68, 0.15);
  color: #fecdd3;
  border-radius: 999px;
  padding: 0.25rem 0.55rem;
  font-size: 0.9rem;
}

@keyframes snowfall {
  from {
    transform: translateY(-10px);
  }
  to {
    transform: translateY(20px);
  }
}

@media (max-width: 640px) {
  .card { padding: 1.1rem; }
  .tile { font-size: 1.1rem; }
}