:root {
  --bg: #0b1020;
  --bg-soft: #121830;
  --card: #1a2137;
  --border: #2a3350;
  --text: #e8ecff;
  --muted: #8b93b5;
  --accent: #6c8cff;
  --accent-2: #39d98a;
  --accent-3: #ff6c9c;
  --radius: 18px;
}

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

body {
  font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
  background-image:
    radial-gradient(600px 400px at 15% 10%, rgba(108, 140, 255, .18), transparent),
    radial-gradient(600px 400px at 85% 90%, rgba(57, 217, 138, .12), transparent);
}

.app {
  width: 100%;
  max-width: 560px;
}

.screen { display: none; }
.screen.active { display: block; animation: fade .25s ease; }

@keyframes fade {
  from { opacity: 0; transform: translateY(8px); }
  to   { opacity: 1; transform: none; }
}

.hero { text-align: center; margin-bottom: 36px; }
.logo { font-size: 2.4rem; font-weight: 800; letter-spacing: -1px; }
.logo span { color: var(--accent); }
.tagline { color: var(--muted); margin-top: 8px; font-size: 1.05rem; }

.card-grid { display: grid; gap: 20px; grid-template-columns: 1fr 1fr; }

.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px 20px;
  cursor: pointer;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
  color: var(--text);
  transition: transform .18s ease, border-color .18s ease, box-shadow .18s ease;
}

.card:hover {
  transform: translateY(-4px);
  border-color: var(--accent);
  box-shadow: 0 18px 40px rgba(0, 0, 0, .4);
}

.card-icon { font-size: 2.4rem; }
.card-title { font-weight: 700; font-size: 1.05rem; }
.card-desc { color: var(--muted); font-size: .85rem; }

.screen-header {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 24px;
}

.screen-header h2 { font-size: 1.4rem; flex: 1; }

.back {
  background: var(--card);
  border: 1px solid var(--border);
  color: var(--text);
  width: 40px; height: 40px;
  border-radius: 12px;
  font-size: 1.2rem;
  cursor: pointer;
}

.back:hover { border-color: var(--accent); }

.score {
  background: var(--card);
  border: 1px solid var(--border);
  padding: 8px 16px;
  border-radius: 999px;
  font-weight: 700;
  color: var(--accent-2);
}

#snake-canvas {
  width: 100%;
  max-width: 400px;
  aspect-ratio: 1;
  display: block;
  margin: 0 auto;
  background: var(--bg-soft);
  border: 1px solid var(--border);
  border-radius: var(--radius);
}

.controls {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  justify-content: center;
  margin-top: 20px;
}

.hint { width: 100%; text-align: center; color: var(--muted); font-size: .8rem; }

.btn {
  padding: 12px 22px;
  border-radius: 12px;
  border: 1px solid var(--border);
  background: var(--card);
  color: var(--text);
  font-weight: 600;
  font-size: .95rem;
  cursor: pointer;
  transition: opacity .15s ease, border-color .15s ease;
}

.btn:hover:not(:disabled) { border-color: var(--accent); }
.btn:disabled { opacity: .4; cursor: not-allowed; }
.btn.primary { background: var(--accent); border-color: var(--accent); color: #fff; }
.btn.primary:hover:not(:disabled) { filter: brightness(1.1); }
.btn.ghost { background: transparent; }

.timer-display {
  font-size: 3.2rem;
  font-weight: 800;
  text-align: center;
  font-variant-numeric: tabular-nums;
  margin: 40px 0 28px;
  padding: 24px;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
}

.timer-presets {
  display: flex;
  gap: 10px;
  justify-content: center;
  margin-bottom: 24px;
  flex-wrap: wrap;
}

.chip {
  background: var(--bg-soft);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 8px 16px;
  border-radius: 999px;
  cursor: pointer;
  font-size: .85rem;
}

.chip:hover, .chip.active { border-color: var(--accent-2); color: var(--accent-2); }

@media (max-width: 480px) {
  .card-grid { grid-template-columns: 1fr; }
  .timer-display { font-size: 2.4rem; }
}