This is an epic signup form by Himalaya Singh where all the fields are hidden away and only shown to the user when it’s needed. When you hover over the Signup Lable you see the micro-interaction in effect and the text field for email is presented, then in the next step, you can add the user name and then the password.
If you are having trouble with the pen, try the archived copy on GitHub
Signup Form Snippet
See the Pen Sign Up Form With Progressive Disclosure | Micro Interaction by Himalaya Singh (@himalayasingh) on CodePen.default