.banqi-board {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 3px;
  width: min(86vw, 300px);
  margin: 10px auto;
  aspect-ratio: 1 / 1;
}
.bq-cell {
  border-radius: 8px;
  background: var(--surface-2);
  display: grid;
  place-items: center;
  font-size: 20px;
  font-weight: 700;
  cursor: pointer;
  position: relative;
}
.bq-cell.down {
  background: #6b5b4f;
  color: transparent;
}
.bq-cell.red { color: #d33; }
.bq-cell.black { color: #1a1a2e; }
.bq-cell.sel {
  outline: 3px solid #ffd93d;
}
.bq-cell.movable {
  box-shadow: inset 0 0 0 3px rgba(107, 202, 119, 0.8);
}
.hud b { color: var(--ink); }