takahe/templates/settings/_settings_system_menu.html

<nav>
    <a href="/settings/system/basic/" {% if section == "basic" %}class="selected"{% endif %}>Basic</a>
    <a href="/settings/system/domains/" {% if section == "domains" %}class="selected"{% endif %}>Domains</a>
    <a href="/settings/system/users/" {% if section == "users" %}class="selected"{% endif %}>Users</a>
</nav>