bs4simplenav.html

<div class="container-fluid">
    <nav class="navbar navbar-light bg-faded">
        <a class="navbar-brand" href="#">Logo (this tag is optional)</a>
        <ul class="nav navbar-nav">
            <li class="nav-item"><a class="nav-link" href="#">Link 1</a></li>
            <li class="nav-item"><a class="nav-link" href="#">Link 2</a></li>
            <li class="nav-item dropdown">
                <a class="nav-link dropdown-toggle" data-toggle="dropdown" href="#" role="button" aria-haspopup="true" aria-expanded="false">
Dropdown</a>
                <ul class="dropdown-menu" aria-labelledby="Preview">
                    <li class="dropdown-item"><a href="#">Dropdown Link 1</a></li>
                    <li class="dropdown-item"><a class="dropdown-item" href="#">Dropdown Link 2</a></li>
                    <li class="dropdown-item"><a class="dropdown-item" href="#">Dropdown Link 3</a></li>
                </div>
            </li>
        </ul>
    </nav>
</div>