css - Bootstrap -在导航栏中将表单与表单控件输入-sm垂直对齐

<nav class="navbar navbar-expand-lg navbar-light bg-light">
  <a class="navbar-brand" href="#">Logo</a>
  <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarNav" aria-controls="navbarNav" aria-expanded="false" aria-label="Toggle navigation">
    <span class="navbar-toggler-icon"></span>
  </button>
  <div class="collapse navbar-collapse" id="navbarNav">
    <ul class="navbar-nav">
      <li class="nav-item active">
        <a class="nav-link" href="#">Home</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">About</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">Contact</a>
      </li>
    </ul>
    <form class="form-inline ml-auto">
      <div class="form-group">
        <input type="text" class="form-control" placeholder="Username">
      </div>
      <div class="form-group">
        <input type="password" class="form-control" placeholder="Password">
      </div>
      <button type="submit" class="btn btn-primary">Login</button>
    </form>
  </div>
</nav>