nav.php

wp_nav_menu(
  array(
		//'theme_location'  => 'header-menu',
		//'menu'            => 'Top nav',
		'depth'      => 2,
        'container'  => 'div',
        'container_class' => 'collapse navbar-collapse navbar-ex1-collapse',
        'menu_class' => 'nav navbar-nav',
        'fallback_cb' => 'wp_bootstrap_navwalker::fallback',
        'walker' => new wp_bootstrap_navwalker()
		)
	);