Alexey Moloko

$(function() {
    var onScroll;
    onScroll = function(e) {
      var $nav_items, active_cls, scrollPos;
      scrollPos = $(document).scrollTop() + 91;
      $nav_items = $('.menu-box').find('.link');
      active_cls = '-active';
      return $nav_items.each(function() {
        var $refElement, refElement_height;
        $refElement = $($(this).attr('href'));
        refElement_height = $refElement.height() + parseInt($refElement.css('paddingBottom')) + parseInt($refElement.css('paddingTop'));
        if ($refElement.length) {
          if ($refElement.offset().top <= scrollPos && $refElement.offset().top + refElement_height > scrollPos) {
            $nav_items.removeClass(active_cls);
            return $(this).addClass(active_cls);
          } else {
            return $(this).removeClass(active_cls);
          }
        }
      });
    };

.wp-block-embed__wrapper:before{
	padding: 0 !important;
}

<div class="container">
  <a href="/" class="home">Главная</a>
  <div class="form-box">
    <form role="search" method="get" class="flex" action="form.php" >
      <input type="search" class="search_field_menu" placeholder="Поиск по сайту" required autocomplete="off" value="" />
      <button type="submit" class="search_submit_menu" value="найти"></button>
    </form>
  </div>
  <?php
    wp_nav_menu( array(
      'theme_location'  => 'nav_top',
      'container'       => 'nav',
      'menu_class'      => '',
      'items_wrap'      => '<ul>%3$s</ul>'
    ));
  ?>
</div>