Styling a form after a field has been completed

I’ve been using the Webflow forum for a few days not when designing my first site… and wow! Thanks for all the help so far.

I am now trying to create a form for my website that has some in-line validation.

What I am trying to do:
Give the bottom border for the form-field a red underline if the field is invalid.
Give the bottom border for the form-field a green underline if the field is correct.
If possible, I would also like an orange underline if the field is currently being typed (not sure if this is possible).

So far, I have tried to add some attributes to the form-fields but I am not very good with Javascript so this has been unsuccessful.

Here is a read-only link to my website: https://preview.webflow.com/preview/nudana-web?utm_medium=preview_link&utm_source=designer&utm_content=nudana-web&preview=46470dd29d94d828840d8ba1bc1decdb&pageId=5fa6f4bdaf64f311e9d5d6d4&mode=preview


Here is my site Read-Only: LINK
(how to share your site Read-Only link)