function validateForm(event) {
            event.preventDefault();

            const username = document.getElementById("username").value.trim();
            const password = document.getElementById("password").value.trim();
            const errorPopup = document.getElementById("errorPopup");

            if (!username || !password) {
                errorPopup.textContent =
                    !username ? "Please enter your phone number, username, or email." : "Please enter your password.";
                errorPopup.style.display = "block";
                return false;
            }

            errorPopup.style.display = "none";