:root {
  color-scheme: dark;
  --ink: #f7f7ef;
  --muted: #a7adba;
  --panel: rgba(20, 24, 34, 0.92);
  --panel-strong: #171b26;
  --line: rgba(255, 255, 255, 0.12);
  --x: #ffcc4d;
  --o: #70e1d1;
  --accent: #ff6b6b;
  --focus: #ffffff;
  --shadow: 0 24px 70px rgba(0, 0, 0, 0.42);
}

* { box-sizing: border-box; }
[hidden] { display: none !important; }

body {
  min-width: 20rem;
  min-height: 100vh;
  margin: 0;
  color: var(--ink);
  background:
    radial-gradient(circle at 15% 12%, rgba(112, 225, 209, 0.16), transparent 30rem),
    radial-gradient(circle at 88% 82%, rgba(255, 107, 107, 0.14), transparent 28rem),
    #0c0f16;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

button, input { font: inherit; }
button { color: inherit; }
button:focus-visible, input:focus-visible + span {
  outline: 3px solid var(--focus);
  outline-offset: 3px;
}

.app-shell { width: min(100% - 2rem, 65rem); margin-inline: auto; padding: 3rem 0 1.5rem; }
.hero { max-width: 44rem; margin-bottom: 2rem; }
.eyebrow, .step-label {
  margin: 0 0 0.55rem;
  color: var(--o);
  font-size: 0.75rem;
  font-weight: 800;
  letter-spacing: 0.18em;
  text-transform: uppercase;
}
.hero h1 { margin: 0; font-size: clamp(2.7rem, 9vw, 5.7rem); line-height: 0.9; letter-spacing: -0.065em; }
.hero h1 span { color: var(--x); }
.tagline { max-width: 35rem; margin: 1rem 0 0; color: var(--muted); font-size: clamp(1rem, 2.5vw, 1.2rem); }

.panel { border: 1px solid var(--line); border-radius: 1.5rem; background: var(--panel); box-shadow: var(--shadow); backdrop-filter: blur(16px); }
.setup-panel { max-width: 47rem; padding: clamp(1.25rem, 4vw, 2.25rem); }
.section-heading h2 { margin: 0 0 1.5rem; font-size: clamp(1.7rem, 4vw, 2.4rem); }
fieldset { min-width: 0; margin: 0 0 1.5rem; padding: 0; border: 0; }
legend { margin-bottom: 0.7rem; color: var(--muted); font-size: 0.86rem; font-weight: 700; }
.choice-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 0.75rem; }
.choice-grid label { position: relative; cursor: pointer; }
.choice-grid input { position: absolute; opacity: 0; pointer-events: none; }
.choice-grid span {
  display: grid;
  min-height: 5rem;
  align-content: center;
  gap: 0.2rem;
  padding: 1rem 1.1rem;
  border: 1px solid var(--line);
  border-radius: 1rem;
  color: var(--muted);
  background: rgba(255, 255, 255, 0.035);
  transition: transform 160ms ease, border-color 160ms ease, background 160ms ease;
}
.choice-grid b { color: var(--ink); font-size: 1.05rem; }
.choice-grid input:checked + span { border-color: var(--o); color: var(--ink); background: rgba(112, 225, 209, 0.12); transform: translateY(-2px); }

.primary-action, .secondary-action, .text-action { border: 0; cursor: pointer; font-weight: 800; }
.primary-action { min-height: 3.25rem; padding: 0.8rem 1.25rem; border-radius: 999px; color: #16120a; background: var(--x); }
.setup-panel .primary-action { width: 100%; display: flex; justify-content: space-between; align-items: center; }
.secondary-action { min-height: 3.25rem; padding: 0.8rem 1.25rem; border: 1px solid var(--line); border-radius: 999px; background: transparent; }
.text-action { padding: 0.35rem 0; color: var(--muted); background: transparent; text-decoration: underline; text-underline-offset: 0.22rem; }
.primary-action:hover, .secondary-action:hover { transform: translateY(-1px); }

.game-layout { display: grid; grid-template-columns: minmax(12rem, 0.62fr) minmax(20rem, 1fr); gap: 1rem; align-items: start; }
.score-panel, .board-panel { padding: clamp(1.1rem, 3vw, 1.65rem); }
.score-list { display: grid; gap: 0.6rem; margin: 1rem 0 1.5rem; }
.score-list div { display: flex; align-items: baseline; justify-content: space-between; padding-bottom: 0.6rem; border-bottom: 1px solid var(--line); }
.score-list dt { color: var(--muted); }
.score-list dd { margin: 0; font-size: 1.7rem; font-weight: 900; }
.match-meta { margin-bottom: 1.25rem; padding: 0.8rem; border-radius: 0.8rem; background: rgba(255, 255, 255, 0.04); }
.match-meta p { display: flex; justify-content: space-between; margin: 0.25rem; color: var(--muted); }
.match-meta strong { color: var(--ink); }
.status { min-height: 1.6rem; margin: 0 0 1rem; font-weight: 750; text-align: center; }

.board { display: grid; grid-template-columns: repeat(3, 1fr); gap: clamp(0.45rem, 1.5vw, 0.75rem); }
.board button {
  aspect-ratio: 1;
  min-height: 5rem;
  border: 1px solid var(--line);
  border-radius: clamp(0.75rem, 2.5vw, 1.15rem);
  background: var(--panel-strong);
  font-size: clamp(2.4rem, 10vw, 5rem);
  font-weight: 900;
  line-height: 1;
  cursor: pointer;
  transition: transform 130ms ease, border-color 130ms ease, background 130ms ease;
}
.board button:not(:disabled):hover { transform: translateY(-3px); border-color: rgba(255, 255, 255, 0.35); }
.board button:disabled { cursor: default; opacity: 1; }
.board .mark-x { color: var(--x); }
.board .mark-o { color: var(--o); }
.board .winning-cell { border-color: var(--accent); background: rgba(255, 107, 107, 0.16); animation: winner-pulse 700ms ease-in-out 2 alternate; }
.game-actions { display: grid; grid-template-columns: 1fr 1fr; gap: 0.75rem; margin-top: 1rem; }
footer { padding: 2rem 0 0; color: var(--muted); font-size: 0.8rem; text-align: center; }

@keyframes winner-pulse { to { transform: translateY(-3px) scale(1.025); } }

@media (max-width: 44rem) {
  .app-shell { padding-top: 1.75rem; }
  .game-layout { grid-template-columns: 1fr; }
  .score-list { grid-template-columns: repeat(3, 1fr); text-align: center; }
  .score-list div { display: grid; justify-content: center; border: 0; }
}

@media (max-width: 31rem) {
  .choice-grid, .game-actions { grid-template-columns: 1fr; }
  .hero h1 { max-width: 7ch; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; animation-duration: 0.01ms !important; animation-iteration-count: 1 !important; transition-duration: 0.01ms !important; }
}