.gst-container {
      width: 100%;
      max-width: 500px;
      background: #fff;
      border-radius: 16px;
      padding: 30px;
      box-shadow: 0 10px 25px rgba(0,0,0,0.08);
    }

    .gst-container h1 {
      text-align: center;
      margin-bottom: 25px;
      color: #222;
      font-size: 32px;
    }

    .input-group {
      margin-bottom: 20px;
    }

    .input-group label {
      display: block;
      margin-bottom: 8px;
      font-weight: 600;
      color: #444;
    }

    .input-group input,
    .input-group select {
      width: 100%;
      padding: 14px;
      border: 1px solid #ddd;
      border-radius: 10px;
      font-size: 16px;
      outline: none;
      transition: 0.3s;
    }

    .input-group input:focus,
    .input-group select:focus {
      border-color: #007bff;
    }

    .radio-group {
      display: flex;
      gap: 20px;
      margin-top: 10px;
    }

    .radio-group label {
      display: flex;
      align-items: center;
      gap: 8px;
      font-weight: 500;
      cursor: pointer;
    }

    .result-box {
      background: #f8fbff;
      border-radius: 12px;
      padding: 20px;
      margin-top: 20px;
      border: 1px solid #dbe8ff;
    }

    .result-item {
      display: flex;
      justify-content: space-between;
      margin-bottom: 14px;
      font-size: 17px;
    }

    .result-item:last-child {
      margin-bottom: 0;
      padding-top: 14px;
      border-top: 1px solid #ddd;
      font-weight: bold;
      font-size: 20px;
      color: #007bff;
    }

    .btn-reset {
      width: 100%;
      margin-top: 20px;
      padding: 14px;
      background: #007bff;
      color: #fff;
      border: none;
      border-radius: 10px;
      font-size: 16px;
      cursor: pointer;
      transition: 0.3s;
    }

    .btn-reset:hover {
      background: #005fd1;
    }

    @media(max-width: 500px) {
      .gst-container {
        padding: 20px;
      }

      .gst-container h1 {
        font-size: 26px;
      }
    }