custom-walker.php

<?php
/**
 * Custom Walker
 *
 * @access      public
 * @since       1.0
 * @return      void
*/
class lflegal_walker extends Walker_Nav_Menu
{
	function start_el(&$output, $item, $depth, $args) {
		 global $wp_query;
		 $indent = ( $depth ) ? str_repeat( "\t", $depth ) : '';

		 $class_names = $value = '';

		 $classes = empty( $item->classes ) ? array() : (array) $item->classes;

		 $class_names = join( ' ', apply_filters( 'nav_menu_css_class', array_filter( $classes ), $item ) );
		 $class_names = ' class="'. esc_attr( $class_names ) . '"';

		 $output .= $indent . '<li id="menu-item-'. $item->ID . '"' . $value . $class_names .'>';

		 $attributes  = ! empty( $item->attr_title ) ? ' title="'  . esc_attr( $item->attr_title ) .'"' : '';
		 $attributes .= ! empty( $item->target )     ? ' target="' . esc_attr( $item->target     ) .'"' : '';
		 $attributes .= ! empty( $item->xfn )        ? ' rel="'    . esc_attr( $item->xfn        ) .'"' : '';
		 $attributes .= ! empty( $item->url )        ? ' href="'   . esc_attr( $item->url        ) .'"' : '';
		 $attributes .= ! empty( $item->destination )        ? ' aui-destination="'   . esc_attr( $item->destination        ) .'"' : '';

		 $prepend = '<strong>';
		 $append = '</strong>';
		 $description  = ! empty( $item->description ) ? '<span>'.esc_attr( $item->description ).'</span>' : '';

		 if($depth != 0)
		 {
			 $description = $append = $prepend = "";
		 }

		$item_output = $args->before;
		$item_output .= '<a'. $attributes .'>';
		$item_output .= $args->link_before .$prepend.apply_filters( 'the_title', $item->title, $item->ID ).$append;
		$item_output .= $description.$args->link_after;
		$item_output .= '</a>';
		$item_output .= $args->after;

		$output .= apply_filters( 'walker_nav_menu_start_el', $item_output, $item, $depth, $args );
		}
}

menu-primary.php

<?php
/**
 * Primary menu.
 *
 * @package Toivo Lite
 */
?>
<div id="menu-primary-wrap" class="nav-wrap">
	<button id="nav-toggle"><?php _e( 'Menu', 'toivo-lite' ); ?></button>

	<nav id="menu-primary" class="menu main-navigation" role="navigation" aria-label="<?php esc_attr_e( 'Primary Menu', 'toivo-lite' ); ?>" <?php hybrid_attr( 'menu', 'primary' ); ?>>
			<?php

				wp_nav_menu(
					array(
						'theme_location'  => 'primary',
						'container'				=> '',
						'menu_id'         => 'menu-primary-items',
						'depth'           => 4,
						'menu_class'      => 'menu-items',
						'walker'					=> new lflegal_walker
					)
				);

				get_search_form();
			?>
	</nav><!-- #menu-primary -->
</div>

menu.js

mainMenu.accessibleMegaMenu({
			uuidPrefix: "primary-menu",
		});