hazelnut.dev/templates/header.html

<header>
    <h1 class="site-title">{{ config.title }}</h1>
    <nav id="navbar">
        <ul>
            {% for item in config.extra.menu %}
                <li>
                    <a class="{% if not item.external %}internal{% endif %}" href="{{ item.url | safe | replace(from="$BASE_URL", to=config.base_url) }}">
                        {{ item.name }}
                    </a>
                </li>
            {% endfor %}
        </ul>
    </nav>
</header>