Struggle Form Card Validation CSS Vanilla Javascript

The html and CSS was easy, the actual coding was not. I spent two days trying to get the javascript to work right with no success. Adding one thing breaks something else.

I validated the form using a for loop which works perfectly, but when it's time to submit, the form either doesn't go through or the CSS changes either act wonky or don't go through, or the form isn't responsive at all.

How can I stop the confirmation div from appearing even if the form isn't validated on click?