<!-- A grey horizontal navbar that becomes vertical on small screens -->
<nav class="navbar navbar-expand-sm bg-light">

  <!-- Links -->
  <ul class="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">
      <a class="nav-link" href="#">Link 3</a>
    </li>
  </ul>

</nav> 

 <!-- A vertical navbar -->
<nav class="navbar bg-light">

  <!-- Links -->
  <ul class="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">
      <a class="nav-link" href="#">Link 3</a>
    </li>
  </ul>

</nav> 

<!-- Grey with black text -->
<nav class="navbar navbar-expand-sm bg-light navbar-light">
  <ul class="navbar-nav">
    <li class="nav-item active">
      <a class="nav-link" href="#">Active</a>
    </li>
    <li class="nav-item">
      <a class="nav-link" href="#">Link</a>
    </li>
    <li class="nav-item">
      <a class="nav-link" href="#">Link</a>
    </li>
    <li class="nav-item">
      <a class="nav-link disabled" href="#">Disabled</a>
    </li>
  </ul>
</nav>

<!-- Black with white text -->
<nav class="navbar navbar-expand-sm bg-dark navbar-dark">...</nav>

<!-- Blue with white text -->
<nav class="navbar navbar-expand-sm bg-primary navbar-dark">...</nav>

 <nav class="navbar navbar-expand-sm bg-dark navbar-dark">
  <a class="navbar-brand" href="#">Logo</a>
  ...
</nav> 

 <nav class="navbar navbar-expand-sm bg-dark navbar-dark">
   <a class="navbar-brand" href="#">
    <img src="bird.jpg" alt="Logo" style="width:40px;">
  </a>
  ...
</nav> 

 <nav class="navbar navbar-expand-md bg-dark navbar-dark">
  <!-- Brand -->
  <a class="navbar-brand" href="#">Navbar</a>

  <!-- Toggler/collapsibe Button -->
  <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#collapsibleNavbar">
    <span class="navbar-toggler-icon"></span>
  </button>

  <!-- Navbar links -->
  <div class="collapse navbar-collapse" id="collapsibleNavbar">
    <ul class="navbar-nav">
      <li class="nav-item">
        <a class="nav-link" href="#">Link</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">Link</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">Link</a>
      </li>
    </ul>
  </div>
</nav> 

 <nav class="navbar navbar-expand-sm bg-dark navbar-dark">
  <!-- Brand -->
  <a class="navbar-brand" href="#">Logo</a>

  <!-- Links -->
  <ul class="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>

    <!-- Dropdown -->
    <li class="nav-item dropdown">
      <a class="nav-link dropdown-toggle" href="#" id="navbardrop" data-toggle="dropdown">
        Dropdown link
      </a>
      <div class="dropdown-menu">
        <a class="dropdown-item" href="#">Link 1</a>
        <a class="dropdown-item" href="#">Link 2</a>
        <a class="dropdown-item" href="#">Link 3</a>
      </div>
    </li>
  </ul>
</nav> 

 <nav class="navbar navbar-expand-sm bg-dark navbar-dark">
  <form class="form-inline" action="/action_page.php">
    <input class="form-control mr-sm-2" type="text" placeholder="Search">
    <button class="btn btn-success" type="submit">Search</button>
  </form>
</nav> 

 <nav class="navbar navbar-expand-sm bg-dark navbar-dark">
  <form class="form-inline" action="/action_page.php">
    <div class="input-group">
      <span class="input-group-addon">@</span>
      <input type="text" class="form-control" placeholder="Username">
    </div>
  </form>
</nav> 

 <nav class="navbar navbar-expand-sm bg-dark navbar-dark">

<!-- Links -->
  <ul class="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>
  </ul>

  <!-- Navbar text-->
  <span class="navbar-text">
    Navbar text
  </span>

</nav> 

 <nav class="navbar navbar-expand-sm bg-dark navbar-dark fixed-top">
  ...
</nav> 

 <nav class="navbar navbar-expand-sm bg-dark navbar-dark fixed-bottom">
  ...
</nav> 

 <nav class="navbar navbar-expand-sm bg-dark navbar-dark sticky-top">
  ...
</nav>