WordPress Code Reference

nav_menu_css_class

Summery Summery

Filters the CSS classes applied to a menu item’s list item element.

apply_filters( 'nav_menu_css_class', string[] $classes, WP_Post $item, stdClass $args, int $depth )

$classes: Array of the CSS classes that are applied to the menu item's <li> element.
$item: The current menu item.
$args: An object of wp_nav_menu() arguments.
$depth: Depth of menu item. Used for padding.

Changelog
Version	Description
4.1.0	The `$depth` parameter was added.
3.0.0	Introduced.