.go-board {
  display: grid;
  grid-template-columns: repeat(9, 1fr);
  gap: 2px;
  width: min(92vw, 360px);
  margin: 12px auto;
  aspect-ratio: 1 / 1;
  background: #e3b96b;
  padding: 4px;
  border-radius: 8px;
}
.go-cell {
  border-radius: 50%;
  background: transparent;
  display: flex; align-items: center; justify-content: center;
  cursor: pointer;
}
.go-cell .stone { width: 86%; height: 86%; border-radius: 50%; }
.go-cell .b { background: #1c1c1c; }
.go-cell .w { background: #fafafa; border: 1px solid #999; }