Pod Request Access Landing Page with HTML, CSS and JS

Hi, everyone! I struggled with the form validation with this one. I didn't know how to change to style of the automatic browser message with submitting an invalid <input type='email'> tag, so I added the 'novalidate' attribute on my <form> tag and did the verification entirely in JS with regex. There's probably a better way to do this. I appreciate any suggestion that you may have about this, as well as the rest of my code. The comments help so much. Thank you all!