gistfile1.cs

@using (Html.BeginForm(null, null, FormMethod.Post, new { @class = "form-signin" })) {
    <h3>Scan Your Promo Code</h3>

    <table class="form-group">
        <tr>
            <td>
                @Html.TextBoxFor(mm => mm.PromoCode, new { placeholder = "Promo code", autofocus = "", @class = "form-control" })
            </td>
            @if (Request.UserAgent.Contains("XamarinBarcodeSampleApp"))
            {
                <td>
                    <button id="scanBarcode" class="btn btn-info btn-block" type="submit">Scan</button>
                </td>
            }
        </tr>
    </table>
    
    <button class="btn btn-lg btn-primary btn-block" type="submit">Register</button>
}