.game-board {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-around;
  width: 40vw;
  height: 40vw;
}
.button-cell {
  position: relative;
  display: flex;
  flex: 0 0 32%;
  justify-content: center;
  align-items: center;
  min-height: 10vw;
  min-width: 10vw;
  margin-bottom: 0.5vw;
  border: 1px solid;
  border-radius: 2px;
  border-color: gray;
  box-shadow: 1px 1px gray;
}
.button-cell:after {
  content: "";
  display: block;
  padding-bottom: 100%;
}
.cell-content {
  justify-content: center;
  align-items: center;
  text-align: center;
  color: white;
}
.X {
  background-color: #0099ff;
}
.O {
  background-color: #00cc33;
}
.active-cell {
  border: 2px solid white;
}