:root {
  color-scheme: dark;
  --bg: #0b1020;
  --card: rgba(255, 255, 255, 0.08);
  --card-border: rgba(255, 255, 255, 0.14);
  --modal-bg: rgba(11, 16, 32, 0.82);
  --modal-border: rgba(255, 255, 255, 0.18);
  --modal-backdrop: rgba(0, 0, 0, 0.55);
  --text: rgba(255, 255, 255, 0.92);
  --muted: rgba(255, 255, 255, 0.7);
  --cell: rgba(255, 255, 255, 0.1);
  --cell-border: rgba(255, 255, 255, 0.18);
  --focus: #9ae6ff;
  --x: #8ad7ff;
  --o: #ffb86b;
  --win: rgba(92, 255, 173, 0.28);
  --page-bg: radial-gradient(1200px 800px at 20% 15%, rgba(138, 215, 255, 0.25), transparent 60%),
    radial-gradient(900px 700px at 80% 30%, rgba(255, 184, 107, 0.2), transparent 55%),
    radial-gradient(800px 600px at 50% 85%, rgba(92, 255, 173, 0.14), transparent 55%), var(--bg);
}

:root[data-theme="light"] {
  color-scheme: light;
  --bg: #f7f9ff;
  --card: rgba(11, 16, 32, 0.06);
  --card-border: rgba(11, 16, 32, 0.14);
  --modal-bg: rgba(255, 255, 255, 0.96);
  --modal-border: rgba(11, 16, 32, 0.16);
  --modal-backdrop: rgba(11, 16, 32, 0.35);
  --text: rgba(11, 16, 32, 0.92);
  --muted: rgba(11, 16, 32, 0.66);
  --cell: rgba(11, 16, 32, 0.06);
  --cell-border: rgba(11, 16, 32, 0.18);
  --focus: #0066cc;
  --x: #0077cc;
  --o: #c95b00;
  --win: rgba(0, 150, 80, 0.18);
  --page-bg: radial-gradient(1200px 800px at 20% 15%, rgba(0, 119, 204, 0.12), transparent 60%),
    radial-gradient(900px 700px at 80% 30%, rgba(201, 91, 0, 0.1), transparent 55%),
    radial-gradient(800px 600px at 50% 85%, rgba(0, 150, 80, 0.1), transparent 55%), var(--bg);
}

* {
  box-sizing: border-box;
}

html,
body {
  height: 100%;
}

body {
  margin: 0;
  font-family: ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial, "Apple Color Emoji",
    "Segoe UI Emoji";
  background: var(--page-bg);
  color: var(--text);
}

.app {
  min-height: 100%;
  display: grid;
  place-items: center;
  padding: 28px 16px;
}

.header {
  text-align: center;
  margin-bottom: 14px;
}

.title {
  margin: 0;
  letter-spacing: 0.5px;
}

.subtitle {
  margin: 6px 0 0;
  color: var(--muted);
}

.card {
  width: min(92vw, 460px);
  background: var(--card);
  border: 1px solid var(--card-border);
  border-radius: 16px;
  padding: 16px;
  backdrop-filter: blur(10px);
  box-shadow: 0 10px 50px rgba(0, 0, 0, 0.35);
}

.status-card {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 56px;
  margin-bottom: 12px;
}

.status-card .status {
  text-align: center;
}

.top-row {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: 12px;
  margin-bottom: 12px;
}

.controls {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
  justify-content: flex-end;
}

.status {
  margin: 0;
  font-weight: 600;
  letter-spacing: 0.2px;
}

.button {
  appearance: none;
  border: 1px solid var(--cell-border);
  background: rgba(255, 255, 255, 0.12);
  color: var(--text);
  border-radius: 10px;
  padding: 10px 12px;
  cursor: pointer;
  font-weight: 600;
}

.button:hover {
  background: rgba(255, 255, 255, 0.16);
}

.button:focus-visible {
  outline: 3px solid var(--focus);
  outline-offset: 2px;
}

.icon-button {
  padding: 0;
  width: 44px;
  height: 44px;
  border-radius: 999px;
  display: grid;
  place-items: center;
}

.theme-toggle {
  position: fixed;
  top: calc(16px + env(safe-area-inset-top));
  right: calc(16px + env(safe-area-inset-right));
  z-index: 10;
}

.theme-toggle .icon {
  display: none;
}

:root:not([data-theme="light"]) .theme-toggle .icon--sun {
  display: block;
}

:root:not([data-theme="light"]) .theme-toggle .icon--moon {
  display: none;
}

:root[data-theme="light"] .theme-toggle .icon--moon {
  display: block;
}

:root[data-theme="light"] .theme-toggle .icon--sun {
  display: none;
}

.modal {
  width: min(92vw, 520px);
  border: 1px solid var(--modal-border);
  border-radius: 16px;
  padding: 16px;
  background: var(--modal-bg);
  color: var(--text);
  box-shadow: 0 20px 80px rgba(0, 0, 0, 0.45);
  backdrop-filter: blur(12px);
}

.modal:not([open]) {
  display: none;
}

.modal::backdrop {
  background: var(--modal-backdrop);
}

.modal-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}

.modal-title {
  margin: 0;
  font-size: 1.2rem;
}

.modal-body {
  margin-top: 10px;
}

.modal-lead {
  margin: 0 0 12px;
  color: var(--muted);
}

.modal-section-title {
  margin: 14px 0 8px;
  font-size: 1rem;
}

.modal-list {
  margin: 0;
  padding-left: 18px;
  line-height: 1.5;
}

.board {
  width: min(92vw, 420px);
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 10px;
}

.cell {
  border: 1px solid var(--cell-border);
  background: var(--cell);
  border-radius: 14px;
  aspect-ratio: 1 / 1;
  font-size: clamp(48px, 10vw, 72px);
  font-weight: 800;
  color: var(--text);
  cursor: pointer;
  display: grid;
  place-items: center;
  user-select: none;
}

.cell[aria-disabled="true"] {
  cursor: not-allowed;
}

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

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

.cell.is-win {
  background: var(--win);
  border-color: rgba(92, 255, 173, 0.55);
}

.cell:focus-visible {
  outline: 3px solid var(--focus);
  outline-offset: 2px;
}

.help {
  margin: 14px 0 0;
  color: var(--muted);
  line-height: 1.35;
  font-size: 0.95rem;
}