.km-board {
  display: grid;
  gap: 2px;
  margin: 0 auto;
  background: var(--line);
  border: 2px solid var(--line);
  border-radius: 8px;
  overflow: hidden;
  touch-action: manipulation;
}
.km-cell {
  aspect-ratio: 1 / 1;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: clamp(15px, 5vw, 22px);
  font-weight: 700;
  background: #fff;
  color: #222;
  cursor: pointer;
  user-select: none;
  transition: background .12s, color .12s;
}
.km-cell.black { background: #1f2937; color: #fff; }
.km-cell.unknown { background: #eef1f6; color: #c2c8d2; }
.km-cell.clue { background: #fff7e6; color: #b45309; }
.km-cell.fixed { cursor: default; }
.km-cell.wrong { box-shadow: inset 0 0 0 2px #ef4444; }