WordPress中的Nav菜单折叠按钮无法折叠

Question

我只希望菜单可折叠以显示移动布局，但我尝试修复均等标记按钮，但仍无法正常工作

  

'front-page.php   导航菜单只是查看按钮而不显示菜单'

<nav class="navbar navbar-expand-md navbar-light bg-light fixed-top" role="navigation">
        <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#div" aria-controls="div" aria-expanded="false" aria-label="Toggle navigation">
          <span class="navbar-toggler-icon"></span>
        </button>
        <a class="navbar-brand" href="#">Navbar</a>
        <container class="collapse navbar-collapse" id='div'>
          <nav class="navbar-item">
            <?php
            wp_nav_menu( array(
              'theme_location'    => 'primary',
              'depth'             => 2,
              'container'         => 'div',
              'container_class'   => 'collapse navbar-collapse',
              'container_id'      => 'div',
              'menu_class'        => 'navbar-nav mr-auto',
              'fallback_cb'       => 'WP_Bootstrap_Navwalker::fallback',
              'walker'            => new WP_Bootstrap_Navwalker(),
            ) );
            ?>
          </nav>
        </container>
    </nav>

  

'code function.php'

 if ( ! file_exists( get_template_directory() . '/class-wp-bootstrap-navwalker.php' ) ) {
        // file does not exist... return an error.
        return new WP_Error( 'class-wp-bootstrap-navwalker-missing', __( 'It appears the class-wp-bootstrap-navwalker.php file may be missing.', 'wp-bootstrap-navwalker' ) );
    } else {
        // file exists... require it.
        require_once get_template_directory() . '/class-wp-bootstrap-navwalker.php';
    }

  //Theme support
  function wpb_theme_setup(){
    //nav menus
    register_nav_menus(array(
        'primary' => __('Primary Menu')
    ));

  add_action('after_setup_theme','wpb_theme_setup');