{source}<?php
// Joomla 4 Namespaces
use Joomla\CMS\Factory;
use Joomla\CMS\Router\Route;
use Joomla\CMS\Session\Session;

// Get current user
$user = Factory::getUser();

if ($user->guest) {
// User is not logged in - show login button
$loginUrl = Route::_('/log-yourself-in', false);
echo '<a class="button button-small" id="loginpop" href="' . $loginUrl . '">Login</a>';
} else {
// User is logged in - show logout button
$logoutUrl = Route::_('index.php?option=com_users&task=user.logout&' . Session::getFormToken() . '=1', false);
echo '<a class="button button-pink" id="loginpop" href="' . $logoutUrl . '">Logout</a>';
}
?>{/source}