navbar navbar-expand-md navbar-light"> code example

Example 1: bootstrap navbar

<nav class="navbar navbar-expand-lg navbar-light bg-light">
  <a class="navbar-brand" href="#">Navbar</a>
  <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarNavAltMarkup" aria-controls="navbarNavAltMarkup" aria-expanded="false" aria-label="Toggle navigation">
    <span class="navbar-toggler-icon"></span>
  </button>
  <div class="collapse navbar-collapse" id="navbarNavAltMarkup">
    <div class="navbar-nav">
      <a class="nav-item nav-link active" href="#">Home <span class="sr-only">(current)</span></a>
      <a class="nav-item nav-link" href="#">Features</a>
      <a class="nav-item nav-link" href="#">Pricing</a>
      <a class="nav-item nav-link disabled" href="#">Disabled</a>
    </div>
  </div>
</nav>

Example 2: bootstrap nav bar

<div class="pos-f-t">
  <div class="collapse" id="navbarToggleExternalContent">
    <div class="bg-dark p-4">
      <h4 class="text-white">Collapsed content</h4>
      <span class="text-muted">Toggleable via the navbar brand.</span>
    </div>
  </div>
  <nav class="navbar navbar-dark bg-dark">
    <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarToggleExternalContent" aria-controls="navbarToggleExternalContent" aria-expanded="false" aria-label="Toggle navigation">
      <span class="navbar-toggler-icon"></span>
    </button>
  </nav>
</div>