:root {
  --bg0: #0c1218;
  --bg1: #15202b;
  --line: #2a3a4a;
  --text: #eef3f8;
  --muted: #8fa3b5;
  --x: #5ec8ff;
  --o: #ff8f6b;
  --win: #3ecf8e;
  --font: "Segoe UI", system-ui, sans-serif;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  min-height: 100vh;
  display: grid;
  place-items: center;
  font-family: var(--font);
  color: var(--text);
  background:
    radial-gradient(900px 500px at 20% -10%, #1a3a55 0%, transparent 55%),
    radial-gradient(700px 420px at 100% 110%, #3a2218 0%, transparent 50%),
    var(--bg0);
}

.wrap {
  width: min(100vw - 2rem, 26rem);
  padding: 1.5rem 1.25rem 1.75rem;
  background: color-mix(in srgb, var(--bg1) 88%, transparent);
  border: 1px solid var(--line);
  border-radius: 18px;
  backdrop-filter: blur(10px);
  box-shadow: 0 24px 60px rgba(0, 0, 0, 0.35);
}

.head { text-align: center; margin-bottom: 1.25rem; }
h1 { margin: 0; font-size: 1.65rem; font-weight: 650; letter-spacing: 0.02em; }
.sub { margin: 0.4rem 0 0; color: var(--muted); font-size: 0.95rem; min-height: 1.4em; }
.sub.win { color: var(--win); font-weight: 600; }

.board {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0.55rem;
  aspect-ratio: 1;
}

.cell {
  appearance: none;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: rgba(255, 255, 255, 0.03);
  color: var(--text);
  font-size: clamp(2rem, 12vw, 3rem);
  font-weight: 700;
  cursor: pointer;
  transition: background 0.15s ease, transform 0.12s ease, border-color 0.15s;
}

.cell:hover:not(:disabled) {
  background: rgba(255, 255, 255, 0.07);
  transform: translateY(-1px);
}

.cell:disabled { cursor: default; }
.cell.x { color: var(--x); }
.cell.o { color: var(--o); }
.cell.win {
  border-color: var(--win);
  background: color-mix(in srgb, var(--win) 18%, transparent);
  animation: pulse 0.45s ease;
}

@keyframes pulse {
  from { transform: scale(0.96); }
  to { transform: scale(1); }
}

.bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  margin-top: 1.25rem;
}

.btn {
  appearance: none;
  border: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.06);
  color: var(--text);
  border-radius: 999px;
  padding: 0.45rem 1rem;
  font: inherit;
  font-size: 0.9rem;
  cursor: pointer;
}

.btn:hover { background: rgba(255, 255, 255, 0.11); }

.score {
  margin: 0;
  color: var(--muted);
  font-size: 0.85rem;
  white-space: nowrap;
}