/* Keep every board cell at exactly 1/15 of the square board. */
.board {
  grid-template-columns: repeat(15, minmax(0, 1fr));
  grid-template-rows: repeat(15, minmax(0, 1fr));
  overflow: hidden;
}

.square {
  min-width: 0;
  min-height: 0;
  overflow: hidden;
}

.tile {
  width: 82%;
  height: 82%;
  max-width: 82%;
  max-height: 82%;
  aspect-ratio: auto;
  overflow: hidden;
}

.tile b {
  font-size: clamp(11px, 2vw, 26px);
  line-height: 1;
}