BUG: Registration form not working on mobile properly and missing progress indicator

[wickathou]

🐛 Bug Report

Registration pages fail to render properly on mobile views, show error messages that are not easy to understand for non-programmers and lacks a way to show how many sections a participant must fill in to complete the registration form

Registration form doesn't render properly on mobile

Error messages are hard to understand for non-programmers

It doesn't show how many more sections a participant have left to complete the registration process