.reaction-box {
    min-height: 200px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    border-radius: 10px;
    transition: background-color 0.3s ease, transform 0.2s ease;
  }
  
  .reaction-box:active {
    transform: scale(0.98);
  }
  
  .leaderboard {
    margin-top: 30px;
  }

  @keyframes pulseGreen {
    0% {
      box-shadow: 0 0 0 0 rgba(34, 197, 94, 0.7);
    }
    70% {
      box-shadow: 0 0 25px 15px rgba(34, 197, 94, 0);
    }
    100% {
      box-shadow: 0 0 0 0 rgba(34, 197, 94, 0);
    }
  }
  
  .pulse {
    animation: pulseGreen 0.8s ease-out infinite;
  }
  
  .difficulty-selector {
    margin-bottom: 20px;
  }