body {
  text-align: center;
}

#board {
    display: grid;
    grid-template-columns: repeat(3, auto);
    width: 306px;
    margin: 50px auto;
}
.cell {
  font-family: "Permanent Marker", cursive;
  color: rgb(0,250,0);
  width: 100px;
  height: 100px;
  box-shadow: 0 0 0 1px #333333;
  border: 1px solid #333333;
  cursor: pointer;
  line-height: 100px;
  font-size: 60px;
}