Staggered Reveal Sign In Login Block for React

Nothing leaves the page. Sign in waits under a spinner for less than a second, then shows "You're signed in" with the address you typed, and a polite status message says nothing was sent; Sign out brings the form back with your email still filled in and every row open. To wire it for real, post the email and password to your auth endpoint where the code says so, keep the busy state until it answers, then redirect, or show its error under the field it concerns. The eight-character rule here only gates the reveal; a sign-in form shouldn't judge a password's length, so drop the rule and open the last row on any password, or keep it for a sign-up page.

A well-formed email (something, an at sign, a domain with a dot) opens the password row, and eight characters in the password open the last row. A row never closes again: if you change the email to something invalid afterwards, the password row stays, so focus is never taken from a field you are in. Pressing the button still checks every open row and names what is wrong.

A hidden or disabled button leaves a keyboard user with nothing to press and no explanation. Here the button is always there, in a quiet fill, with a label naming the step ("Enter your email", then "Enter your password"); it's marked aria-disabled but can still be pressed, and pressing it says what is missing under the field and moves focus there. Once the form is complete it takes the primary color and reads "Sign in".

The page is centered in the screen, so a row that grew into place would move the heading and the fields already there. The rows to come are in the page the whole time, invisible and removed from the tab order and from assistive technology until they open, and a dashed outline marks where the password will be. When one opens it turns visible at once, so its field can take focus, and eases down into place.

Nothing about what opens or when: the rows still follow the visitor's input. Every entrance and every reveal is a CSS transition that is switched off, so the mark, the heading and the fields are there at once and a row appears the moment it opens, with no delay between rows.

Tab runs through the email, then the password and its show and hide toggle once they have opened, Forgot password, Keep me signed in and the button; a row that hasn't opened is skipped. Opening a row never moves focus, and a polite status message says what opened ("Email accepted. The password field is open."). Each problem is tied to its field, and after signing in focus moves to the result's heading.