{% capture api %}
Return the HTML Bootstrap 4 navbar given in liquid as `include.nav` or `site.nav`. Expected are `right` and `left` arrays with the page title. Array elements containing an array are rendered as dropdowns.

``` yml
left:
  - Home
  - Docs:
    - Tempus
    - Libros
  - Customize:
    - Css
    - Themes
  - About
right:
  - Login
```

- **Usage**

```liquid
{% raw %}{% include page/navbar.html nav=site.data.navbar %}{% endraw %}
```

- **Called by** `_includes/page/top.html` to render main navigation
- **Call** `_includes/components/navbar_link.html` to render singular links
{% endcapture %}
{% include api/save.html %}
{%- assign navigation = include.nav | default: site.navbar -%}
<!-- Navbar -->
<nav class="navbar navbar-expand-md">
	<div class="container{{ fluid }}">
		<button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarHeader" aria-controls="navbarHeader" aria-expanded="false" aria-label="Toggle navigation">
			<span class="navbar-toggler-icon"></span>
		</button>

		<div class="collapse navbar-collapse" id="navbarHeader">
			<ul class="navbar-nav mr-auto">
				{%- for nav in navigation.left -%}
					{%- if nav.first == nil -%}
						{% assign link = site.pages | where:'title', nav | default: [url: nav] %}
						{% include components/navbar_link.html %}
					{%- else -%}
						{%- assign list_title = nav | first | first -%}
						{%- assign list_title_slug = list_title | slugify -%}
						{%- assign list = nav.first[1] -%}
						<!-- Dropdown -->
						<li class="nav-item dropdown">
							<a class="nav-link dropdown-toggle" href="#" id="{{ list_title_slug }}_dropdown" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
							{{ list_title }}
							</a>
							<div class="dropdown-menu" aria-labelledby="{{ list_title_slug }}_dropdown">
								{% for item in list %}
									{%- assign link = site.pages | where:'title', item | default: nil -%}
									<a class="dropdown-item{% if page.url == link[0].url %} active{% endif %}" href="{{ link[0].url }}">{{ item }}{% if page.url == link[0].url %} <span class="sr-only">(current)</span>{% endif %}</a>
								{% endfor %}
							</div>
						</li>
					{%- endif -%}
				{%- endfor -%}
			</ul>
			<ul class="navbar-nav my-lg-0">
				{% for nav in navigation.right %}
				{%- assign link = site.pages | where:'title', nav -%}
				{% include components/navbar_link.html %}
				{% endfor %}
			</ul>
		</div>
	</div>
</nav>