Add class to list

The CMS Questions
1

Hey,
i have this code to add a class to the ul element. But how can i add a class to the li element too?

<?php 
$liste = $page->liste(); 
$liste_ul = preg_replace('/<ul>/', '<ul class="classname">', $liste); 
?>
<?= $liste_ul; ?>
2

preg_replace() accepts an array of patterns and values to replace with, no just single string