/* Theme Selection Cards */
.theme-card-wrapper {
    display: flex;
    flex-wrap: wrap;
    gap: 20px;
    justify-content: center;
    padding: 20px 0;
  }
  .theme-card {
    background: #007bff;
    color: white;
    padding: 20px 30px;
    font-size: 20px;
    border-radius: 10px;
    cursor: pointer;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    transition: transform 0.3s, background 0.3s;
    min-width: 150px;
    text-align: center;
  }
  .theme-card:hover {
    transform: scale(1.05);
  }
  
  /* Card Layout */
  .card {
    position: relative;
    width: 300px;
    height: 400px;
    margin: 30px auto;
    background: white;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    border-radius: 12px;
    overflow: hidden;
    transform-style: preserve-3d;
    transform: perspective(1000px);
    cursor: pointer;
  }
  .card-inner {
    position: absolute;
    width: 100%;
    height: 100%;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    transform-style: preserve-3d;
    transition: transform 0.8s;
  }
  .card.flipped .card-inner {
    transform: rotateY(180deg);
  }
  .card-front, .card-back {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 24px;
    padding: 20px;
    text-align: center;
  }
  .card-front {
    background: #ffcc00;
    color: #333;
  }
  .card-back {
    background: #007bff;
    color: white;
    transform: rotateY(180deg);
  }
  
  /* Navigation Buttons */
  .navigation {
    display: flex;
    justify-content: space-around;
    margin-top: 20px;
  }
  .nav-button {
    background: #28a745;
    color: white;
    border: none;
    border-radius: 8px;
    padding: 10px 15px;
    font-size: 16px;
    cursor: pointer;
    transition: background 0.3s ease;
  }
  .nav-button:hover {
    background: #1e7e34;
  }
  .exit-button {
    background: #dc3545;
  }
  .exit-button:hover {
    background: #b21f2d;
  }