.halma-board {
  display: grid;
  grid-template-columns: repeat(9, 1fr);
  gap: 2px;
  width: min(92vw, 380px);
  margin: 10px auto;
  aspect-ratio: 1 / 1;
}
.hm-cell {
  border-radius: 4px;
  background: var(--surface-2);
  display: grid;
  place-items: center;
  cursor: pointer;
}
.hm-cell.zone-red {
  background: rgba(255, 92, 92, 0.18);
}
.hm-cell.zone-black {
  background: rgba(26, 26, 46, 0.12);
}
.hm-cell.sel { outline: 3px solid #ffd93d; }
.hm-cell.movable { box-shadow: inset 0 0 0 3px rgba(107, 202, 119, 0.85); }
.hm-piece {
  width: 78%;
  height: 78%;
  border-radius: 50%;
}
.hm-piece.red { background: #ff5c5c; }
.hm-piece.black { background: #1a1a2e; }
.hud b { color: var(--ink); }