Adding a linke in the navbar of hugo-creative-theme that is not callpsed in the menu

Hi,

I am trying to add a link in the hugo-creative-theme navbar for switching languages. So that link should be positioned to the left of the remaining links and stay there also in the mobile-version (so it should not be callpased into the menu like the remaining navigation links).

What I tried: I added this to the naviagation div:

<nav id="mainNav" class="navbar navbar-default navbar-fixed-top">
    <div class="container-fluid">
        (... other stuff)
        <!-- this diff and its content is what i added/>
        <div class="navbar-default">
            <ul class="nav navbar-nav navbar-right">
                <li>
                    <a class="navbar-link" href="/en">English</a>
                </li>
            </ul>
        </div>
        (... other stuff)
    </div>
</nav>

But on the mobile version, that link appears in a new line.

How can I do this?

Thanks!