:root {
  color-scheme: dark;
  --bg: #14161a;
  --panel: #20242b;
  --panel-strong: #2b3038;
  --line: #3d4652;
  --text: #f4f0e8;
  --muted: #b7c0ca;
  --x: #51d7b6;
  --o: #ffbf69;
  --accent: #77a7ff;
}

* {
  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 20% 15%, rgba(81, 215, 182, 0.16), transparent 32rem),
    radial-gradient(circle at 78% 8%, rgba(255, 191, 105, 0.13), transparent 30rem),
    linear-gradient(135deg, #14161a 0%, #1b2026 52%, #16181d 100%);
  color: var(--text);
}

button {
  font: inherit;
}

.shell {
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: clamp(1rem, 3vw, 2rem);
}

.game-panel {
  width: min(100%, 34rem);
  display: grid;
  gap: 1rem;
  padding: clamp(1rem, 3vw, 1.5rem);
  background: rgba(32, 36, 43, 0.9);
  border: 1px solid rgba(244, 240, 232, 0.12);
  border-radius: 8px;
  box-shadow: 0 1.5rem 4rem rgba(0, 0, 0, 0.34);
}

.masthead {
  display: grid;
  gap: 0.25rem;
}

.eyebrow {
  margin: 0;
  color: var(--accent);
  font-size: 0.78rem;
  font-weight: 700;
  text-transform: uppercase;
}

h1 {
  margin: 0;
  font-size: clamp(2.1rem, 8vw, 4.2rem);
  line-height: 0.95;
  letter-spacing: 0;
}

.scoreboard {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 0.6rem;
}

.scoreboard div {
  min-width: 0;
  padding: 0.75rem;
  background: var(--panel-strong);
  border: 1px solid var(--line);
  border-radius: 8px;
}

.scoreboard span,
.status {
  color: var(--muted);
}

.scoreboard span {
  display: block;
  font-size: 0.78rem;
  white-space: nowrap;
}

.scoreboard strong {
  display: block;
  margin-top: 0.15rem;
  font-size: 1.6rem;
}

.status {
  min-height: 1.5rem;
  margin: 0;
  font-weight: 650;
}

.board {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: clamp(0.45rem, 2vw, 0.75rem);
  aspect-ratio: 1;
}

.cell {
  display: grid;
  place-items: center;
  min-width: 0;
  aspect-ratio: 1;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: #171a1f;
  color: var(--text);
  cursor: pointer;
  font-size: clamp(3rem, 18vw, 5.8rem);
  font-weight: 900;
  line-height: 1;
  transition: transform 140ms ease, border-color 140ms ease, background 140ms ease;
}

.cell:hover:not(:disabled),
.cell:focus-visible {
  border-color: var(--accent);
  background: #1d2229;
  transform: translateY(-1px);
  outline: none;
}

.cell:disabled {
  cursor: default;
}

.cell.x {
  color: var(--x);
}

.cell.o {
  color: var(--o);
}

.cell.win {
  border-color: currentColor;
  background: rgba(255, 255, 255, 0.08);
}

.actions {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.75rem;
}

.actions button {
  min-height: 2.8rem;
  border: 1px solid var(--line);
  border-radius: 8px;
  color: var(--text);
  cursor: pointer;
  font-weight: 750;
}

.secondary {
  background: var(--panel-strong);
}

.primary {
  background: #355c9f;
  border-color: #5e86ca;
}

@media (max-width: 430px) {
  .game-panel {
    gap: 0.8rem;
  }

  .scoreboard div {
    padding: 0.6rem 0.45rem;
  }

  .scoreboard span {
    font-size: 0.7rem;
  }

  .actions {
    grid-template-columns: 1fr;
  }
}