custom inline form code

Hello, Is it possible to build a completely custom "inline form"? The form builder in CC is very weak, so we were hoping to be able to create our own form that posts to the same endpoint. It appears that CC requires the "Universal JS" code to embed the inline form. Was hoping to basically extract the final HTML that this creates and customize it ourselves before embedding on our website. Is it possible or is there some security/cross-domain stuff going on to prevent us from doing this?