.gomoku-board {
  --board-edge: 6.25%;
  position: relative;
  display: block;
  overflow: visible;
  border: 2px solid #8d7155;
  background: #d9b278;
  touch-action: manipulation;
}

.gomoku-board__lines {
  position: absolute;
  inset: var(--board-edge);
  pointer-events: none;
  background-image:
    linear-gradient(to right, rgba(80, 55, 35, .6) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(80, 55, 35, .6) 1px, transparent 1px);
  background-position: left top;
  background-size: calc(100% / 14) 100%, 100% calc(100% / 14);
  box-shadow:
    inset -1px 0 rgba(80, 55, 35, .6),
    inset 0 -1px rgba(80, 55, 35, .6);
}

.gomoku-board button {
  position: absolute;
  z-index: 1;
  width: 7.1%;
  height: 7.1%;
  min-width: 0;
  padding: 0;
  transform: translate(-50%, -50%);
  border: 0;
  background: transparent;
  touch-action: manipulation;
}

.gomoku-board button::after {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 82%;
  aspect-ratio: 1;
  transform: translate(-50%, -50%);
  border-radius: 50%;
  content: "";
}

.gomoku-board .stone--black::after {
  background: #29252a;
  box-shadow: inset -2px -2px 4px #000, 0 2px 4px rgba(55, 35, 20, .3);
}

.gomoku-board .stone--white::after {
  background: #faf8f3;
  box-shadow: inset -2px -2px 4px #b9b0a6, 0 2px 4px rgba(55, 35, 20, .24);
}