React-Based Intro Component with Sign-in Form

I am redoing this FEM project to incorporate the custom validation into my project. This would have been easier to add with vanilla JavaScript but I am still trying to master ReactJS skills.

The areas I found difficult was:

• custom validation with react using useState method
• removing the placeholder when an error is made and adding the SVG error icon

I am unsure of:

• how to add the email@example/com to the email field when the email field is empty. How would one go about adding it in with ReactJS?

• This is (Extra Credit) but when a user fills out the form completely with no errors, and hit submit, I want to be able to show a FormSucess Message

Regarding Best Practices:

• Have I placed my state logic in the right components for better performance?
• Are there places in my formLogin.js where I can refactor and make it a little cleaner?

Please any other feedback is greatly appreciated