body {
  font-family: Arial, sans-serif;
  text-align: center;
  margin: 0;
  background: #f4f4f4;
}

.hidden {
  display: none;
}

.center {
  margin-top: 100px;
}

.scoreboard {
  display: flex;
  justify-content: space-between;
  padding: 10px 20px;
  font-weight: bold;
}

.board {
  display: grid;
  grid-template-columns: repeat(3, 100px);
  gap: 5px;
  justify-content: center;
  margin: 20px auto;
}

.cell {
  width: 100px;
  height: 100px;
  background: white;
  font-size: 2rem;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  border: 2px solid black;
}

button {
  padding: 10px 20px;
  margin-top: 10px;
  cursor: pointer;
}

/* Responsive */
@media (max-width: 600px) {
  .board {
    grid-template-columns: repeat(3, 70px);
  }
  .cell {
    width: 70px;
    height: 70px;
  }
}