<nav class="navbar navbar-expand-lg navbar-light bg-primary">
    <a class="navbar-brand text-white" href="/">VULNERABILITY WEB APP DEMO</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>
    <div class="collapse navbar-collapse" id="navbarNav">
        <ul class="navbar-nav ml-auto">
            <li class="nav-item">
                <a class="nav-link text-white" href="/about">About</a>
            </li>
            <% if (username) { %>
                <li class="nav-item">
                    <a class="nav-link text-white" href="/logout">Logout (<%= username %>)</a>
                </li>
            <% } %>
        </ul>
    </div>
</nav>