Sign-up form using Javascript for validation

Hi everyone, this is my solution to the challenge. It was really fun but also really challenging at the same time especially the JavaScript. I do have a few bugs though. When I view the implementation on iPhones the heading is chopped off, and when viewed on safari on a Mac it's also not displaying properly. The other problem is, when I resubmit the form for validation, I want it to remove the error texts that are there, instead it doesn't clear them. Anyways, I think those are the two major problems I have encountered. Please let me know if there are other ways I could improve. Thanks :).