public function _nav_menu_css_class( $classes, $item, $args, $depth ) {
		if ( ! is_object( $args->walker ) ) {
			return $classes;
		}

		if ( ! $args->walker instanceof \Inc2734\WP_Basis\App\Walker\Navbar ) {
			return $classes;
		}

		if ( $depth > 0 ) {
			$classes[] = 'c-navbar__subitem';
		} else {
			$classes[] = 'c-navbar__item';
		}

		$classes = array_unique( $classes );

		return $classes;
	}