frappe/frappe/templates/includes/navbar/navbar.html

{%- if theme.based_on == 'Bootstrap 4' -%}
<nav class="bg-white shadow-sm navbar navbar-light navbar-expand-lg sticky-top">
	<div class="container">
		<a class="navbar-brand" href="{{ url_prefix }}{{ home_page or "/" }}">
			<span>{{ brand_html or (frappe.get_hooks("brand_html") or [_("Home")])[0] }}</span>
		</a>
		<button class="navbar-toggler" type="button"
			data-toggle="collapse"
			data-target="#navbarSupportedContent"
			aria-controls="navbarSupportedContent"
			aria-expanded="false"
			aria-label="Toggle navigation">
			<span class="navbar-toggler-icon"></span>
		</button>

		<div class="collapse navbar-collapse" id="navbarSupportedContent">
			{% include "templates/includes/navbar/navbar_items.html" %}
		</div>
	</div>
</nav>
{%- else -%}
{{ c('navbar', theme=theme) }}
{%- endif -%}