.game-board {
  display: grid;
  grid-template-columns: repeat(4, 100px);
  grid-gap: 15px;
  justify-content: center;
  margin: 20px auto;
}

.card {
  width: 100px;
  height: 100px;
  background-color: #FFD700;
  border: 2px solid #000;
  border-radius: 10px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 36px;
  font-weight: bold;
  color: transparent;
  transition: transform 0.3s ease, background-color 0.3s ease;
}

.card.flipped {
  background-color: #333;
  color: #FFD700;
  transform: rotateY(180deg);
}

/* Responsive Design Improvements */
@media (max-width: 1200px) {
  #main-container {
    flex-direction: column;
    align-items: center;
    gap: 20px;
  }

  #wheel-container,
  .game-board,
  #settings-container {
    width: 90%;
    max-width: 500px;
    margin: 0 auto;
  }
}

@media (max-width: 768px) {
  #main-container {
    padding: 10px;
  }

  #spin-btn {
    width: 80px;
    height: 80px;
    font-size: 14px;
  }

  .tabs {
    flex-wrap: wrap;
    gap: 10px;
  }

  .tab-button {
    flex: 1 1 auto;
    text-align: center;
  }

  button {
    font-size: 14px;
    padding: 10px 16px;
  }
}

@media (max-width: 480px) {
  #main-container {
    flex-direction: column;
    gap: 20px;
  }

  #wheel-container {
    max-width: 300px;
    height: auto;
  }

  .game-board {
    grid-template-columns: repeat(3, 80px);
  }

  .cell {
    width: 80px;
    height: 80px;
    font-size: 24px;
  }

  button {
    font-size: 12px;
    padding: 8px 12px;
  }

  .tabs {
    flex-direction: column;
    gap: 5px;
  }
}