ol.gomoku_board {
  background-color: hsl(43, 89%, 38%);
  border: 0.3em outset hsl(43, 89%, 32%);
  font-size: 39px;
  line-height: 0px;
  margin: 1em auto;
  padding-left: 0;
  position: relative;
  width: 15em;
}

ol.gomoku_board:before {
  background-color: hsl(43, 89%, 85%);
  border: 1px solid black;
  content: "";
  height: calc(100% - 1em - 2px);
  left: 0.5em;
  position: absolute;
  top: 0.5em;
  width: calc(100% - 1em - 2px);
}
