带有折叠菜单图标的引导导航栏 - 如何？

Question

在这个引导启动模板上：

当浏览器变窄时，导航栏链接/按钮会折叠成右上角的一个图标，如下所示：

我希望将这个折叠的“图标”作为默认设置，如上图所示。这样导航栏链接在用户单击右上角的折叠按钮后可用。

怎么做？

这是模板的源代码：

<nav class="navbar navbar-inverse navbar-fixed-top">
<div class="container">
    <div class="navbar-header">
      <button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#navbar" aria-expanded="false" aria-controls="navbar">
        <span class="sr-only">Toggle navigation</span>
        <span class="icon-bar"></span>
        <span class="icon-bar"></span>
        <span class="icon-bar"></span>
      </button>
      <a class="navbar-brand" href="#">Project name</a>
    </div>
    <div id="navbar" class="collapse navbar-collapse">
      <ul class="nav navbar-nav">
        <li class="active"><a href="#">Home</a></li>
        <li><a href="#about">About</a></li>
        <li><a href="#contact">Contact</a></li>
      </ul>
    </div><!--/.nav-collapse -->
  </div>
</nav>

<div class="container">

  <div class="starter-template">
    <h1>Bootstrap starter template</h1>
    <p class="lead">Use this document as a way to quickly start any new project.<br> All you get is this text and a mostly barebones HTML document.</p>
  </div>

</div><!-- /.container -->

Answer 1

这一切都在 CSS 中。

查看这篇文章并查看 css 专栏。

Always Collapse Bootstrap Nav

工作示例：

.navbar .navbar-header {
  float: none;
}
.navbar .navbar-toggle {
  display: block;
}
.navbar .navbar-collapse.collapse {
  display: none!important;
}
.navbar .navbar-nav {
  float: none!important;
}
.navbar .navbar-nav > li {
  float: none;
}
.navbar .navbar-collapse.collapse.in {
  display: block !important;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/js/bootstrap.min.js"></script>
<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css" rel="stylesheet" />
<nav class="navbar navbar-inverse navbar-static-top">

  <div class="navbar-header">
    <button type="button" class="navbar-toggle" data-toggle="collapse" data-target="#navbar">
      <span class="icon-bar"></span>
      <span class="icon-bar"></span>
      <span class="icon-bar"></span>
    </button>
    <a class="navbar-brand" href="#">Brand</a>
  </div>

  <div class="navbar-collapse collapse" id="navbar">
    <ul class="nav navbar-nav">
      <li class="active"><a href="#">Home</a>
      </li>
      <li><a href="#about">About</a>
      </li>
      <li><a href="#contact">Contact</a>
      </li>
    </ul>
  </div>

</nav>