:root {
  --bg: #0b0f17;
  --panel: rgba(255, 255, 255, 0.06);
  --text: rgba(255, 255, 255, 0.92);
  --muted: rgba(255, 255, 255, 0.68);
  --border: rgba(255, 255, 255, 0.14);
  --board: #1e6f3c;
  --board-dark: #175a31;
  --hint: rgba(255, 255, 255, 0.38);
}

* {
  box-sizing: border-box;
}

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

.app {
  max-width: 980px;
  margin: 0 auto;
  padding: 22px 16px 40px;
}

.top h1 {
  margin: 8px 0 10px;
}

.top p {
  margin: 0;
  color: var(--muted);
}

.back {
  color: var(--muted);
  text-decoration: underline;
}

.panel {
  margin-top: 14px;
  border: 1px solid var(--border);
  border-radius: 14px;
  background: var(--panel);
}

.controls {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  padding: 12px;
  align-items: center;
}

.controls label {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  color: var(--muted);
}

select,
button {
  font: inherit;
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 10px;
  background: rgba(255, 255, 255, 0.08);
  padding: 8px 10px;
}

button {
  cursor: pointer;
}

.scorebar {
  display: flex;
  flex-wrap: wrap;
  gap: 18px;
  padding: 12px;
}

.game-wrap {
  padding: 12px;
}

.board {
  width: min(88vw, 620px);
  aspect-ratio: 1;
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(8, 1fr);
  grid-template-rows: repeat(8, 1fr);
  border: 2px solid rgba(0, 0, 0, 0.4);
  border-radius: 8px;
  overflow: hidden;
  background: var(--board);
}

.cell {
  border: 1px solid rgba(0, 0, 0, 0.3);
  background: var(--board);
  display: grid;
  place-items: center;
  padding: 0;
  cursor: pointer;
}

.cell:nth-child(16n + 1),
.cell:nth-child(16n + 3),
.cell:nth-child(16n + 5),
.cell:nth-child(16n + 7),
.cell:nth-child(16n + 10),
.cell:nth-child(16n + 12),
.cell:nth-child(16n + 14),
.cell:nth-child(16n + 16) {
  background: var(--board-dark);
}

.cell:disabled {
  cursor: default;
}

.piece {
  width: 76%;
  height: 76%;
  border-radius: 50%;
  border: 1px solid rgba(0, 0, 0, 0.35);
  box-shadow: inset 0 -4px 8px rgba(0, 0, 0, 0.25);
}

.piece.black {
  background: #101216;
}

.piece.white {
  background: #f2f2f2;
}

.hint {
  width: 22%;
  height: 22%;
  border-radius: 50%;
  background: var(--hint);
}