* {  
      box-sizing: border-box;  
    }  
    html {
      touch-action: manipulation;
    }
    
    body {
      font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
      background: linear-gradient(135deg, #eceff1, #f5f7fa);
      margin: 0;
      padding: 0;
    }
  
    .container {
      padding: 20px;
    }

    .index-container {
      max-width: 500px;
      margin: 0px auto;
      background: #fff;
      border-radius: 8px;
      padding: 40px 20px;
      box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
    }
  
    h1 {
      font-size: 26px;
      margin: 0 0 25px 0;
      text-align: center;
    }
  
    .form-group {  
      margin: 10px 0;  
    }  
  
    label {  
      font-size: 18px;  
      margin-right: 10px;  
    } 
  
    #inputBtn {  
      padding: 10px;  
      font-size: 16px;  
      margin-left: 10px;  
    }  
    #saveBtn {  
      padding: 6px;  
      font-size: 14px;  
    }  
  
    input[type=number] {  
      font-size: 18px;  
      padding: 10px;  
      width: 150px;  
    }  
  
    input[type=submit] {  
      background-color: #4CAF50;  
      border: none;  
      color: white;  
      cursor: pointer;  
      font-size: 18px;  
      padding: 10px;  
      width: 100%;  
    }  
  
    .result-label {  
      font-size: 18px;  
      margin-left: 10px;  
    }  
  
    .result-value {  
      font-size: 24px;  
      font-weight: bold;  
    }  
  .button-container {
    display: flex;
    flex-direction: column;
    align-items: center;
    margin: 20px auto;
    width: 100%;
  }

  .button {
    width: 100%;
    max-width: 320px;
    padding: 12px 20px;
    background-color: #4a90e2;
    color: white;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    text-decoration: none;
    text-align: center;
    margin-bottom: 15px;
    transition: background-color 0.3s ease;
  }

  .button:hover {
    background-color: #357ABD;
  }