index.html

<!DOCTYPE html>
<html lang="es">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Registro de Usuarios</title>
    <link rel="stylesheet" href="styles.css">
</head>
<body>
    <div class="container">
        <h1>Registro de Usuarios</h1>
        <form action="register.php" method="POST" id="registrationForm">
            <label for="username">Nombre de Usuario:</label>
            <input type="text" id="username" name="username" required>

            <label for="password">Contraseña:</label>
            <input type="password" id="password" name="password" required>

            <label for="id">Dni:</label>
            <input type="text" id="id" name="id" required>

            <div class="button-container">
              <button type="submit">Registrar</button>
            </div>
        </form>
        <div id="message"></div>
    </div>
    <script src="script.js"></script>
</body>
</html>