body {
      text-align: center;
      background-color: #011F3F;
      font-family: 'Arial', sans-serif;
      color: white;
      margin: 0;
      padding: 0;
    }
    .app-logo {
      width: 96px;
      height: 96px;
      margin-top: 20px;
      user-select: none;
    }
    h1 {
      font-size: 2rem;
      margin-top: 30px;
    }
    .container {
      margin: 50px auto;
      width: 300px;
      display: grid;
      grid-template-columns: 150px 150px;
      gap: 10px;
    }
    .btn {
      height: 150px;
      width: 150px;
      border-radius: 20px;
      cursor: pointer;
      border: none;
      transition: all 0.1s ease;
    }
    .red {
      background-color: #f94144;
    }
    .green {
      background-color: #90be6d;
    }
    .blue {
      background-color: #577590;
    }
    .yellow {
      background-color: #f9c74f;
    }
    .pressed {
      box-shadow: 0 0 20px white;
      opacity: 0.7;
      transform: scale(0.95);
    }
    .game-over {
      background-color: #ff0000;
      animation: flash 0.2s;
    }
    .wrong {
      filter: brightness(60%);
      animation: flash 0.2s;
    }
    @keyframes flash {
      0%, 100% { opacity: 1; }
      50% { opacity: 0.1; }
    }