Um CSS-Klassen zum WordPress edit_post Button hinzuzufügen kann functions.php einfach erweitert werden:
//Add class to edit button
function custom_edit_post_link($output) {
$output = str_replace('class="post-edit-link"', 'class="post-edit-link btn btn-info"', $output);
return $output;
}
add_filter('edit_post_link', 'custom_edit_post_link');