I have asked the devs about the inline display off these fields. I'll get back to when I have an answer.
As for the class you mention I guess this is a class from Engagebox. At least I aasume you use this to put a module in a popup. If I'm wrong, please tell me where you have found that class.
Best way to go is to add a class suffix to your Subscription module and use that to tarhet the css inside the module.