{%- set depth = config.theme.toc_depth or 3 -%}
{%- macro toc_items(items, level) -%}
<ul>
  {%- for h in items %}
  <li><a href="{{ h.url }}" data-level="{{ h.level }}">{{ h.title }}</a>
    {%- if h.children and h.level < depth %}{{ toc_items(h.children, level + 1) }}{% endif %}
  </li>
  {%- endfor %}
</ul>
{%- endmacro -%}
{%- set items = page.toc.items -%}
{%- if items | length == 1 and items[0].level == 1 -%}{%- set items = items[0].children -%}{%- endif -%}
<nav class="sumi-toc">{{ toc_items(items, 1) }}</nav>