BestNotes/bestnotes/templates/navbar.html

<nav class="navbar navbar-expand-lg navbar-dark bg-primary">
    <a class="navbar-brand" href="#">
        <i class="fa fa-sticky-note logo"></i>
        <strong>Best Notes</strong>
    </a>
    <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarNav" aria-controls="navbarNav" aria-expanded="false" aria-label="Toggle navigation">
        <span class="navbar-toggler-icon"></span>
    </button>
        <ul class="navbar-nav collapse navbar-collapse"  id="navbarNav">
            <li class="nav-item nav-link" href="#">Strona główna <span class="sr-only">(current)</span></li>
            {% if user.is_authenticated %}
            <li class="nav-item nav-link active"><a class="nolink" href="{% url 'subject' %}">Przedmioty</a></li>
            <li class="nav-item nav-link"><a class="nolink" href="{% url 'logout' %}">Wyloguj się</a></li>
            {% endif %}
        </ul>
</nav>