<form method="post" action="https://spg.evopayments.eu/pay/payssl.aspx" target="evoiFrame" id="evoForm">
    <input type="hidden" name="MerchantID" value="{{ merchant_id }}"/>
    <input type="hidden" name="Len" value="{{ length }}"/>
    <input type="hidden" name="Data" value="{{ data }}"/>
    <input type="hidden" name="Language" value="en"/>
    <button type="submit" name="submit" class="checkoutButton" id="evoSubmit" value="submit">
        Make Payment Securely
        <i class="fa fa-lock"></i>
    </button>
</form>
<div id="evopayForm" style="display:none;">
    <iframe name="evoiFrame" width="450" height="400" frameborder="0"></iframe>
</div>
<script>
    $(document).ready(function () {
        $('#evoSubmit').on('click', function (e) {
            $('#evopayForm').slideDown();
        })
    })
</script>