bootstrap_1_3.html

<nav class="navbar bg-dark">
    <button class="navbar-toggler navbar-dark" type="button" data-toggle="collapse" data-target="#navigation">
        <span class="navbar-toggler-icon"></span>
    </button>
    <div class="collapse navbar-collapse" id="navigation">
        <ul class="navbar-nav">
            <li class="nav-item">
                <a class="nav-link" href="#">Home</a>
            </li>
            <li class="nav-item">
                <a class="nav-link" href="#">Seite 1</a>
            </li>
            <li class="nav-item">
                <a class="nav-link" href="#">Seite 2</a>
            </li>
        </ul>
    </div>
</nav>