netbox/netbox/templates/rest_framework/api.html

{% extends 'rest_framework/base.html' %}
{% load static %}

{% block bootstrap_theme %}
    <link rel="stylesheet" type="text/css" href="{% static 'bootstrap-3.4.1-dist/css/bootstrap.min.css' %}"/>
    <link rel="stylesheet" type="text/css" href="{% static "rest_framework/css/bootstrap-tweaks.css" %}"/>
{% endblock %}

{% block branding %}
    <a class="navbar-brand" href="/{{ settings.BASE_PATH }}">NetBox</a>
{% endblock %}