body {
  background-color: #0d1117;
  color: white;
  text-align: center;
  font-family: 'Poppins', sans-serif;
}

#game-board {
  display: grid;
  grid-template-columns: repeat(4, 80px);
  gap: 10px;
  justify-content: center;
  margin-top: 30px;
}

.card {
  width: 80px;
  height: 80px;
  background-color: #21262d;
  border-radius: 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  font-size: 1.5em;
  color: transparent;
  transition: all 0.3s;
}

.card.flipped {
  background-color: #238636;
  color: white;
}