Bootstrap 4中的Bootstrap 4导航栏菜单（移动）风格？

Question

Bootstrap 4示例

Bootstrap 3示例

如何在Bootstrap 3中获取Bootstrap 4菜单？

此代码来自bootstrap 4 http://v4-alpha.getbootstrap.com/examples/navbar/：

<div class="container">
      <nav class="navbar navbar-light bg-faded">
        <button class="navbar-toggler hidden-sm-up" type="button" data-toggle="collapse" data-target="#navbar-header" aria-controls="navbar-header">
          &#9776;
        </button>
        <div class="collapse navbar-toggleable-xs" id="navbar-header">
          <a class="navbar-brand" href="#">Navbar</a>
          <ul class="nav navbar-nav">
            <li class="nav-item active">
              <a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
            </li>
            <li class="nav-item">
              <a class="nav-link" href="#">Features</a>
            </li>
            <li class="nav-item">
              <a class="nav-link" href="#">Pricing</a>
            </li>
            <li class="nav-item">
              <a class="nav-link" href="#">About</a>
            </li>
          </ul>
          <form class="form-inline pull-xs-right">
            <input class="form-control" type="text" placeholder="Search">
            <button class="btn btn-outline-success" type="submit">Search</button>
          </form>
        </div>
      </nav> <!-- /navbar -->
</div><!-- /container -->

Answer 1

你需要在bootstrap 4中添加一些css，我想他们这样做是因为你可以切换不同大小的菜单，所以你需要将媒体查询添加到你希望菜单打开的任何大小。像这样：

这是一个小提琴，其中包含一些自定义样式，用于引导4导航栏Bootstrap 4 Navbar Fiddle

@media(max-width:33.9em) {
  .navbar .collapse {max-height:250px;width:100%;overflow-y:auto;overflow-x:hidden;}
  .navbar .navbar-brand {float:none;display: inline-block;}
  .navbar .navbar-nav>.nav-item { float: none; margin-left: .1rem;}
  .navbar .navbar-nav {float:none !important;}
  .nav-item{width:100%;text-align:left;}
  .navbar .collapse .dropdown-menu {
    position: relative;
    float: none;
    background:none;
    border:none;
  }
}