html, body {
      height: 100%;  
      margin: 0;
    }
    body {
      font-family: Arial, sans-serif;
      display: flex;
      flex-direction: column;  
      justify-content: space-between; 
      line-height: 1.6;
      text-align: center;
      color: #eaf0ff;
      background: url('../image/img_bg.jpg') no-repeat center center;
      background-size: cover;
      background-attachment: fixed;
      overflow-x: hidden;
    }


    @media (max-width: 768px) {
      body {
        background-attachment: scroll;
        background-position: center top;
      }
    }

    header {
      background: rgba(17,26,43,0.7);
      padding: 20px;
      z-index: 2;
    }
    header h1 {
      margin: 0;
      font-size: 24px;
      color: #4f8cff;
    }

    .main-body {
      padding: 60px 20px;
      background: rgba(11,18,32,0.6);
      border-radius: 12px;
      max-width: 800px;
      margin: 40px auto;
    }
    .main-body p {
      font-size: 18px;
      max-width: 700px;
      margin: 0 auto 30px;
    }

    .btn-whatsapp {
      display: inline-block;
      padding: 15px 35px;
      font-size: 18px;
      color: white;
      background: #25D366;
      border-radius: 40px;
      text-decoration: none;
      font-weight: bold;
      box-shadow: 0 0 15px rgba(37, 211, 102, 0.6);
      transition: transform 0.2s, box-shadow 0.2s;
    }
    .btn-whatsapp:hover {
      transform: scale(1.05);
      box-shadow: 0 0 20px rgba(37, 211, 102, 0.8);
    }

    footer {
      background: rgba(17,26,43,0.7);
      color: #a8b3cf;
      padding: 15px;
      font-size: 14px;
    }