Loginout in nav menu with functions

I found this code the other day, it adds a login/logout link in the navigation menu when using menus. It works fine, but I was wondering how I could also add a link to dashboard, as well as style it if possible. I can’t figure out the proper class to use.

add_filter('wp_nav_menu_items', 'add_login_logout_link', 10, 2);
function add_login_logout_link($items, $args) {

        ob_start();
        wp_loginout('index.php');
        $loginoutlink = ob_get_contents();
        ob_end_clean();

        $items .= '<li>'. $loginoutlink .'</li>';

    return $items;
}