Add LI Class for WP Nav Menu

add-li-class-nav-menu.php

<?php 
// Add Formal/Mobile Menu li Class 
function lhcorp_formal_menu_li_classes($classes, $item, $args) {
  if($args->theme_location == 'formal-menu') {
    $classes[] = 'glue-header__item nav-items';
  }
  return $classes;
}
add_filter('nav_menu_css_class', 'lhcorp_formal_menu_li_classes', 1, 3);


// Add Class without menu it's children
function lhcorp_formal_menu_li_classes($classes, $item, $args) {
  if ($args->theme_location == 'formal-menu') {
    // Check if the item is a top-level item, not a child
    if ($item->menu_item_parent == 0) {
      $classes[] = 'glue-header__item nav-items';
    }
  }
  return $classes;
}
add_filter('nav_menu_css_class', 'lhcorp_formal_menu_li_classes', 10, 3);

add-link-class-into-li-item.php

<?php 

// Add Formal/Mobile Menu Link Class 
function lhcorp_formal_menu_add_link_class( $atts, $item, $args ) {
	// Specify the menu location or menu ID you want to target
	$target_menu_location = 'formal-menu'; // Replace with the actual location or menu ID

	// Check if the current menu matches the target menu
	if ($args->theme_location === $target_menu_location) {
			$class = 'glue-header__link nav-link'; // or something based on $item
			$atts['class'] = $class;
	}

	return $atts;
}
add_filter( 'nav_menu_link_attributes', 'lhcorp_formal_menu_add_link_class', 10, 3 );

add-or-customize-menu-container-class.php

<?php 

// Add or Customize Mobile/Formal Menu Container Class
function remove_mobile_menu_container_class($args) {
	// Check if the menu is for the mobile menu location.
	if ($args['theme_location'] == 'formal-menu') {
			$args['container_class'] = 'glue-header__link-bar';
	}
	return $args;
}
add_filter('wp_nav_menu_args', 'remove_mobile_menu_container_class');

Container, List Item, Menu Item Class