4.17: Correction

formulaire.html

<!DOCTYPE html>
<html lang="fr">
	<head>
		<meta charset="utf-8"/>
		<title>Texte</title>
		<style>
			.erreur{
				color: red;
				transition: opacity .3s;
			}
		</style>
	</head>
	<body>
		<h1>Vos identifiants:</h1>
		<form method="POST">
			<p>
				<label>Nom : <input id="nom" type="text"/></label> 
				<span class="erreur" id="erreur-nom">Non valide !</span>
			</p>
			<p>
				<label>Login : <input id="login" type="text"/></label> 
			</p>
			<p>
				<label>Mot de passe : <input id="mdp" type="password"/></label> 
				<span class="erreur" id="erreur-mdp">Trop court !</span>
			</p>
			<p>
				<label>Confirmation : <input id="confirmation" type="password"/></label> 
				<span class="erreur" id="erreur-confirmation">Différents !</span>
			</p>
			<p>
				<input id="submit" type="submit" value="Envoyer"/>
			</p>
		</form>
		<script src="formulaire.js"></script>
	</body>
</html>