I have panels into frame=true Panel...

I wish that this panels, into frame panel, there are your background as transparent...

Is possible?

<%@ Page Language="vb"%>
<%@ Register Assembly="Ext.Net" Namespace="Ext.Net" TagPrefix="ext" %>

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
    <script type="text/javascript">

        Ext.onReady(function () {

            var viewPort = Ext.create("Ext.net.Viewport", {
                id: "vpMain",
                renderTo: Ext.getBody(),
                layout: 'fit',
                padding: 20
            });

            var mainPanel = viewPort.add({
                itemId: 'mainPanel',
                layout: 'fit',
                flex: 1,
                frame: true,
                bodyPadding: 20
            });

            var pane2 = mainPanel.add({
                itemId: 'pane2',
                layout: 'fit',
                flex: 1,
                border: false,
                bodyPadding: 20
            });

            var txt1 = pane2.add({
                itemId: 'txt1',
                xtype: 'textfield',
                fieldLabel: 'txt1',
                labelAlign: 'top',
                layout: {
                    type: 'hbox'
                }
            });


        });

    </script>

</head>
<body>
    <ext:ResourceManager ID="ResourceManager1" theme="Gray" runat="server" />
    <form id="form1" runat="server">
    </form>
</body>
</html>