如何在wordpress wp\\u nav\\u菜单的当前页面上添加css类

For Example I Want To Use It In Wordpress wp_nav_menu

<li><a href="index.php?id=index&colortheme=green" class="selected" title="Home">Home</a></li>

Wordpress Code

<?php $menu_args = array(\'menu\' => \'Header\' ); wp_nav_menu( $menu_args ); ?>

Using This Function

function add_nav_class($output) {
$output= preg_replace(\'/<a/\', \'<a class="selected"\', $output, 1);
return $output;
}
add_filter(\'wp_nav_menu\', \'add_nav_class\');

but this function select only home and not highlight current page item thanks in advance