body {
  font-family: sans-serif;
  text-align: center;
}

#game-board {
  display: grid;
  grid-template-columns: repeat(5, 60px);
  grid-gap: 10px;
  justify-content: center;
  margin-top: 20px;
}

.cell {
  width: 60px;
  height: 60px;
  background: #f0f0f0;
  font-size: 20px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  border: 1px solid #999;
}

.cell.clicked {
  background: #b2f2bb;
}

#message {
  margin-top: 20px;
  font-size: 18px;
  color: #444;
}