It's bit odd. You would want the form to be handled by Django forms system or wtforms in Flask - and having third party package to provice CSS for the classes t

It's bit odd. You would want the form to be handled by Django forms system or wtforms in Flask - and having third party package to provice CSS for the classes they used (or you use on a wrapper element). And you can make reusable components with Jinja or Django templates as well.