document.getElementById('button-user').addEventListener('click', function(event) {
            var username = document.getElementById("username").value;
            if (username === null || username === "") {
                alert(username);
            } else {
                var user = document.getElementById('usern');
                user.classList.add("hidden");
                var pass = document.getElementById('passwor');
                pass.classList.remove("hidden");
                var spanElement = document.getElementById("lgnid");
                spanElement.textContent = username;
                document.getElementById("storedu").value = username;
            }
        });