:root {
  color-scheme: dark;
  --bg: #101329;
  --panel: #191f3f;
  --panel-2: #202852;
  --ink: #f6f2ff;
  --muted: #b8b6d6;
  --accent: #ffd166;
  --cyan: #66e3ff;
  --pink: #ff77ba;
  --green: #9cff9b;
  --danger: #ff8a8a;
}

* { box-sizing: border-box; }
body {
  margin: 0;
  min-height: 100vh;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background:
    radial-gradient(circle at 18% 14%, rgba(102, 227, 255, 0.18), transparent 28rem),
    radial-gradient(circle at 86% 18%, rgba(255, 119, 186, 0.16), transparent 26rem),
    linear-gradient(145deg, #0b0d1f, var(--bg));
  color: var(--ink);
}

.shell { width: min(980px, 100%); margin: 0 auto; padding: 18px; }
.top-nav { display: flex; gap: 12px; flex-wrap: wrap; margin-bottom: 24px; }
.top-nav a {
  color: var(--ink); text-decoration: none; border: 1px solid rgba(255,255,255,.18);
  background: rgba(255,255,255,.07); padding: 9px 13px; border-radius: 999px;
}
.top-nav a:hover { border-color: var(--cyan); }
.hero, .game-card, .rules {
  background: rgba(25,31,63,.82); border: 1px solid rgba(255,255,255,.12);
  box-shadow: 0 22px 55px rgba(0,0,0,.28); border-radius: 26px; padding: clamp(18px, 4vw, 32px);
  backdrop-filter: blur(12px); margin-bottom: 18px;
}
.eyebrow, .label { color: var(--muted); text-transform: uppercase; letter-spacing: .08em; font-size: .74rem; }
h1 { font-size: clamp(2.4rem, 9vw, 5.2rem); margin: 4px 0 10px; line-height: .95; }
.lede { color: var(--muted); font-size: 1.12rem; max-width: 62ch; }
.status-row { display: grid; grid-template-columns: repeat(3, 1fr); gap: 10px; margin-bottom: 18px; }
.status-row div { background: var(--panel-2); border-radius: 18px; padding: 12px; }
.status-row strong { display: block; margin-top: 4px; font-size: 1.35rem; }
.board-wrap { display: grid; place-items: center; overflow: auto; padding: 8px 0; }
.board { display: grid; grid-template-columns: repeat(7, minmax(38px, 64px)); gap: 6px; touch-action: manipulation; }
.cell {
  width: clamp(38px, 11vw, 64px); aspect-ratio: 1; border: 0; border-radius: 14px;
  background: #111735; color: var(--ink); font-size: clamp(1.2rem, 5vw, 2rem);
  display: grid; place-items: center; position: relative; box-shadow: inset 0 0 0 1px rgba(255,255,255,.09);
}
.cell.open { cursor: pointer; }
.cell.open:hover { background: #1d2858; }
.cell.wall { background: #080b1a; color: #5d668c; }
.cell.start { background: rgba(255, 209, 102, .16); color: var(--accent); }
.cell.prism { background: rgba(102, 227, 255, .13); color: var(--cyan); }
.cell.prism.lit { background: rgba(156, 255, 155, .18); color: var(--green); box-shadow: 0 0 22px rgba(156,255,155,.35), inset 0 0 0 1px rgba(156,255,155,.45); }
.cell.path::after {
  content: ""; position: absolute; inset: 37% 12%; border-radius: 999px;
  background: linear-gradient(90deg, transparent, var(--accent), transparent); opacity: .86; transform: rotate(var(--beam-angle, 0deg));
}
.cell.mirror { color: var(--pink); text-shadow: 0 0 12px rgba(255,119,186,.6); }
.message { color: var(--muted); background: rgba(255,255,255,.06); border-radius: 16px; padding: 13px 15px; margin: 18px 0; min-height: 3rem; }
.message.win { color: var(--green); }
.message.warn { color: var(--danger); }
.controls { display: flex; gap: 10px; flex-wrap: wrap; }
button {
  border: 0; border-radius: 999px; padding: 12px 16px; color: #101329; background: var(--accent);
  font-weight: 800; cursor: pointer; box-shadow: 0 8px 22px rgba(0,0,0,.22);
}
button.secondary, #clearBtn { background: var(--cyan); }
button:disabled { opacity: .45; cursor: not-allowed; }
.rules h2 { margin-top: 0; }
.rules li { margin: 8px 0; color: var(--muted); }
@media (max-width: 560px) {
  .shell { padding: 12px; }
  .status-row { grid-template-columns: 1fr; }
  .board { gap: 4px; }
  .cell { border-radius: 10px; }
}