sidebar_nav-collections.liquid (for three menu level)

{% assign current_menu = {{sidebar_nav-collections}} %}
{% capture menu_size %} {{ linklists[current_menu].links | size }} {% endcapture %}
<ul class="top-menu collections-menu size-{{ menu_size | lstrip | rstrip }}">

    {% for link in linklists[current_menu].links %}

        {% assign child_list_handle = link.title | handleize %}

        {% if linklists[child_list_handle].links != blank %}

            {% assign submenu_active = false %}
            {% for childlink in linklists[child_list_handle].links %}
                {% if childlink.active %}
                    {% assign submenu_active = true %}
                {% endif %}
            {% endfor %}

            <li class="submenu{% if link.active or submenu_active %} selected{% endif %}" aria-haspopup="true">
                <a href="{{ link.url }}">
                    {{ link.title }}
                    {% include 'asset_svg' with 'arrow_icon' %}
                </a>
                <ul class="sub-menu">
                    {% assign grand_child_list_handle = childlink.title | handle %}

                    {% if linklists[grand_child_list_handle] and linklists[grand_child_list_handle].links.size > 0 %}

                        <li class="thirdmenu">
                            <a href="{{ link.url }}">
                                {{ childlink.title }}
                                {% include 'asset_svg' with 'arrow_icon' %}
                            </a>

                            <ul class="third-menu">
                                {% for grand_childlink in linklists[grand_child_list_handle].links %}
                                    <li>
                                      {{ grand_childlink.title | link_to: grand_childlink.url }}
                                    </li>
                                {% endfor %}
                            </ul>
                        </li>

                    {% else %}

                        <li{% if childlink.active %} class="selected"{% endif %}><a href="{{ childlink.url }}">{{ childlink.title | escape }}</a></li>

                    {% endif %}
                {% endfor %}
                </ul>
            </li>

        {% else %}

            <li{% if link.active %} class="selected"{% endif %}>
                <a href="{{ link.url }}">{{ link.title }}</a>
            </li>

        {% endif %}

    {% endfor %}

</ul>