lightswitch change size of checkbox (in code)

I in need to resize the editor generated checkbox. Since it didn't work to make it bigger in the designer (neighter setting pixels nor min. width/height) i gave it a try with code:

Private Sub ESDLogbuch_Created()
        AddHandler Me.FindControl("pass").ControlAvailable, AddressOf PassBox_ControlAvailable

    End Sub

Private Sub PassBox_ControlAvailable(sender As Object, e As ControlAvailableEventArgs)
        Dim chkbx As CheckBox
        chkbx = TryCast(e.Control, CheckBox)
        chkbx.Height = 20
        chkbx.Width = 20


    End Sub

it has an effect on the whole control, but not on the box itself.. i might also say i activated the LightSwitch Cosmopolitan Shell and Theme

thanks in advance!