Email register website with validation

=== Re-done on 2 September 2021. ===

• Added proper email custom validation in JS.
• Improved accessibility for error messages.

=== This is original issues raised in July 2021 ===

This is my first submission on frontendmentor. I could not solve below, however most of design is satisfactory;

• Hover on arrow button: hover does not work on buttons?
• Background image: do I need repeat and gradient? I could not figure out to do the same as original design.
• addEventListener('submit', function (){} : it did not work, so I used click instead to show error messages and icon.

I appreciate if you provide me good feedbacks.

Many thanks