html, body {
    margin: 0;
    padding: 0;
    height: 100%;
  }
  
  .large-header {
    position: relative;
    width: 100%;
    height: 100%;
    background: #333;
    overflow: hidden;
    background-size: cover;
    background-position: center center;
    z-index: 1;
    transition: filter 0.3s;
  }
  
  #large-header {
    background-image: url("1bg.jpg");
    background-size: cover;
    height: 100%;
  }
  
  .main-title {
    position: absolute;
    margin: 0;
    padding: 0;
    color: #f9f1e9;
    text-align: center;
    top: 50%;
    left: 50%;
    -webkit-transform: translate3d(-50%, -50%, 0);
    transform: translate3d(-50%, -50%, 0);
  }
  
  .demo-1 .main-title {
    text-transform: uppercase;
    font-size: 4.2em;
    letter-spacing: 0.1em;
  }
  
  .main-title .thin {
    font-weight: 200;
  }

  .main-title .ultrathin {
    font-weight: 50;
    font-size: 0.7em;
  }
  
  @media only screen and (max-width: 768px) {
    .demo-1 .main-title {
      font-size: 3em;
    }
  }

  .start-button {
    position: absolute;
    top: 60%;
    left: 50%;
    transform: translateX(-50%);
    padding: 15px 30px;
    font-size: 1.5em;
    color: #fff;
    background: rgba(0, 105, 146, 0.8);
    border: none;
    border-radius: 5px;
    cursor: pointer;
    transition: background 0.2s ease-in-out;
    border-radius: 16px;
    box-shadow: 0 4px 30px rgba(0, 0, 0, 0.1);
    backdrop-filter: blur(8.5px);
    -webkit-backdrop-filter: blur(3px);
  }
  
  .start-button:hover {
    background: rgba(0, 105, 146, 0.2);

  }

  .game-container {
    display: none;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    text-align: center;
    background: rgba(0, 0, 0, 0.4);
    padding: 20px;
    border-radius: 10px;
    z-index: 2;
    backdrop-filter: blur(5px);
    -webkit-backdrop-filter: blur(3px);
  }
  
  .game-container img {
    max-width: 100%;
    border: 2px solid #fff;
    border-radius: 5px;
  }
  
  .answer-input {
    width: calc(50% - 40px);
    padding: 10px;
    margin: 10px 0;
    font-size: 1em;
    border: none;
    border-radius: 5px;
    outline: none;
    text-align: center;
  }
  
  .submit-button {
    padding: 10px 20px;
    font-size: 1em;
    color: #fff;
    background: rgba(0, 105, 146, 0.8);
    border: none;
    border-radius: 5px;
    cursor: pointer;
    transition: background 0.3s, transform 0.3s;
    visibility:visible;
  }
  
  .submit-button:hover {
    background: rgba(0, 105, 146, 0.2);
    transform: scale(1.1);
  }
  
  .submit-button:active {
    transform: scale(1.05);
  }
  
  .feedback {
    color: #fff;
    font-size: 1.2em;
    margin-top: 10px;
  }