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导航栏

Bootstrap 强大的响应式导航标题导航栏的文档和示例。包括对品牌、导航等的支持，包括对我们的折叠插件的支持。

在本页面

这个怎么运作

在开始使用导航栏之前，您需要了解以下内容：

导航栏需要一个用于响应式折叠和.navbar配色方案类的包装。.navbar-expand{-sm|-md|-lg|-xl|-xxl}
默认情况下，导航栏及其内容是流动的。更改容器以不同方式限制其水平宽度。
使用我们的间距和flex实用程序类来控制导航栏中的间距和对齐方式。
导航栏默认情况下是响应式的，但您可以轻松修改它们以更改它。响应行为取决于我们的 Collapse JavaScript 插件。
通过使用<nav>元素来确保可访问性，或者，如果使用更通用的元素，例如 a <div>，则将 a 添加role="navigation"到每个导航栏，以明确将其标识为辅助技术用户的标志性区域。
通过aria-current="page"用于当前页面或aria-current="true"集合中的当前项目来指示当前项目。

该组件的动画效果依赖于 prefers-reduced-motion媒体查询。请参阅我们可访问性文档的减少运动部分。

支持的内容

导航栏内置了对少数子组件的支持。根据需要从以下选项中进行选择：

.navbar-brand为您的公司、产品或项目名称。
.navbar-nav用于全高度和轻量级导航（包括对下拉菜单的支持）。
.navbar-toggler用于我们的折叠插件和其他导航切换行为。
适用于任何表单控件和操作的 Flex 和间距实用程序。
.navbar-text用于添加垂直居中的文本字符串。
.collapse.navbar-collapse用于按父断点分组和隐藏导航栏内容。
添加一个可选项.navbar-scroll来设置max-height和滚动扩展的导航栏内容。

这是响应式轻主题导航栏中包含的所有子组件的示例，该导航栏会在lg（大）断点处自动折叠。

<nav class="navbar navbar-expand-lg navbar-light bg-light">
  <div class="container-fluid">
    <a class="navbar-brand" href="#">Navbar</a>
    <button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
      <span class="navbar-toggler-icon"></span>
    </button>
    <div class="collapse navbar-collapse" id="navbarSupportedContent">
      <ul class="navbar-nav me-auto mb-2 mb-lg-0">
        <li class="nav-item">
          <a class="nav-link active" aria-current="page" href="#">Home</a>
        </li>
        <li class="nav-item">
          <a class="nav-link" href="#">Link</a>
        </li>
        <li class="nav-item dropdown">
          <a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button" data-bs-toggle="dropdown" aria-expanded="false">
            Dropdown
          </a>
          <ul class="dropdown-menu" aria-labelledby="navbarDropdown">
            <li><a class="dropdown-item" href="#">Action</a></li>
            <li><a class="dropdown-item" href="#">Another action</a></li>
            <li><hr class="dropdown-divider"></li>
            <li><a class="dropdown-item" href="#">Something else here</a></li>
          </ul>
        </li>
        <li class="nav-item">
          <a class="nav-link disabled">Disabled</a>
        </li>
      </ul>
      <form class="d-flex">
        <input class="form-control me-2" type="search" placeholder="Search" aria-label="Search">
        <button class="btn btn-outline-success" type="submit">Search</button>
      </form>
    </div>
  </div>
</nav>

此示例使用背景( bg-light) 和间距( my-2, my-lg-0, me-sm-0, my-sm-0) 实用程序类。

牌

.navbar-brand可以应用于大多数元素，但锚点效果最好，因为某些元素可能需要实用程序类或自定义样式。

文本

在类的元素中添加您的文本.navbar-brand。

<!-- As a link -->
<nav class="navbar navbar-light bg-light">
  <div class="container-fluid">
    <a class="navbar-brand" href="#">Navbar</a>
  </div>
</nav>

<!-- As a heading -->
<nav class="navbar navbar-light bg-light">
  <div class="container-fluid">
    <span class="navbar-brand mb-0 h1">Navbar</span>
  </div>
</nav>

图片

您可以将中的文本替换.navbar-brand为<img>.

<nav class="navbar navbar-light bg-light">
  <div class="container">
    <a class="navbar-brand" href="#">
      <img src="/docs/5.1/assets/brand/bootstrap-logo.svg" alt="" width="30" height="24">
    </a>
  </div>
</nav>

图片和文字

您还可以使用一些其他实用程序同时添加图像和文本。注意.d-inline-block和.align-text-top的添加<img>。

<nav class="navbar navbar-light bg-light">
  <div class="container-fluid">
    <a class="navbar-brand" href="#">
      <img src="/docs/5.1/assets/brand/bootstrap-logo.svg" alt="" width="30" height="24" class="d-inline-block align-text-top">
      Bootstrap
    </a>
  </div>
</nav>

<nav class="navbar navbar-expand-lg navbar-light bg-light">
  <div class="container-fluid">
    <a class="navbar-brand" href="#">Navbar</a>
    <button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-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">
          <a class="nav-link active" aria-current="page" href="#">Home</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 disabled">Disabled</a>
        </li>
      </ul>
    </div>
  </div>
</nav>

而且因为我们为导航使用类，如果您愿意，您可以完全避免使用基于列表的方法。

<nav class="navbar navbar-expand-lg navbar-light bg-light">
  <div class="container-fluid">
    <a class="navbar-brand" href="#">Navbar</a>
    <button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-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-link active" aria-current="page" href="#">Home</a>
        <a class="nav-link" href="#">Features</a>
        <a class="nav-link" href="#">Pricing</a>
        <a class="nav-link disabled">Disabled</a>
      </div>
    </div>
  </div>
</nav>

您还可以在导航栏中使用下拉菜单。下拉菜单需要一个包装元素来定位，因此请务必使用单独和嵌套的元素，.nav-item如下.nav-link所示。

<nav class="navbar navbar-expand-lg navbar-light bg-light">
  <div class="container-fluid">
    <a class="navbar-brand" href="#">Navbar</a>
    <button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#navbarNavDropdown" aria-controls="navbarNavDropdown" aria-expanded="false" aria-label="Toggle navigation">
      <span class="navbar-toggler-icon"></span>
    </button>
    <div class="collapse navbar-collapse" id="navbarNavDropdown">
      <ul class="navbar-nav">
        <li class="nav-item">
          <a class="nav-link active" aria-current="page" href="#">Home</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 dropdown">
          <a class="nav-link dropdown-toggle" href="#" id="navbarDropdownMenuLink" role="button" data-bs-toggle="dropdown" aria-expanded="false">
            Dropdown link
          </a>
          <ul class="dropdown-menu" aria-labelledby="navbarDropdownMenuLink">
            <li><a class="dropdown-item" href="#">Action</a></li>
            <li><a class="dropdown-item" href="#">Another action</a></li>
            <li><a class="dropdown-item" href="#">Something else here</a></li>
          </ul>
        </li>
      </ul>
    </div>
  </div>
</nav>

形式

在导航栏中放置各种表单控件和组件：

<nav class="navbar navbar-light bg-light">
  <div class="container-fluid">
    <form class="d-flex">
      <input class="form-control me-2" type="search" placeholder="Search" aria-label="Search">
      <button class="btn btn-outline-success" type="submit">Search</button>
    </form>
  </div>
</nav>

.navbar使用 flex 布局的直接子元素，默认为justify-content: space-between. 根据需要使用其他flex 实用程序来调整此行为。

<nav class="navbar navbar-light bg-light">
  <div class="container-fluid">
    <a class="navbar-brand">Navbar</a>
    <form class="d-flex">
      <input class="form-control me-2" type="search" placeholder="Search" aria-label="Search">
      <button class="btn btn-outline-success" type="submit">Search</button>
    </form>
  </div>
</nav>

输入组也可以工作。如果您的导航栏是一个完整的表单，或者大部分是一个表单，您可以使用该<form>元素作为容器并保存一些 HTML。

<nav class="navbar navbar-light bg-light">
  <form class="container-fluid">
    <div class="input-group">
      <span class="input-group-text" id="basic-addon1">@</span>
      <input type="text" class="form-control" placeholder="Username" aria-label="Username" aria-describedby="basic-addon1">
    </div>
  </form>
</nav>

这些导航栏表单也支持各种按钮。这也是一个很好的提醒，垂直对齐实用程序可用于对齐不同大小的元素。

<nav class="navbar navbar-light bg-light">
  <form class="container-fluid justify-content-start">
    <button class="btn btn-outline-success me-2" type="button">Main button</button>
    <button class="btn btn-sm btn-outline-secondary" type="button">Smaller button</button>
  </form>
</nav>

文本

导航栏可能会在.navbar-text. 此类调整文本字符串的垂直对齐和水平间距。

<nav class="navbar navbar-light bg-light">
  <div class="container-fluid">
    <span class="navbar-text">
      Navbar text with an inline element
    </span>
  </div>
</nav>

根据需要与其他组件和实用程序混合搭配。

<nav class="navbar navbar-expand-lg navbar-light bg-light">
  <div class="container-fluid">
    <a class="navbar-brand" href="#">Navbar w/ text</a>
    <button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#navbarText" aria-controls="navbarText" aria-expanded="false" aria-label="Toggle navigation">
      <span class="navbar-toggler-icon"></span>
    </button>
    <div class="collapse navbar-collapse" id="navbarText">
      <ul class="navbar-nav me-auto mb-2 mb-lg-0">
        <li class="nav-item">
          <a class="nav-link active" aria-current="page" href="#">Home</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>
      </ul>
      <span class="navbar-text">
        Navbar text with an inline element
      </span>
    </div>
  </div>
</nav>

配色方案

background-color由于主题类和实用程序的结合，对导航栏进行主题化从未如此简单。选择.navbar-light用于浅色背景色或.navbar-dark深色背景色。然后，使用.bg-*实用程序进行自定义。

<nav class="navbar navbar-dark bg-dark">
  <!-- Navbar content -->
</nav>

<nav class="navbar navbar-dark bg-primary">
  <!-- Navbar content -->
</nav>

<nav class="navbar navbar-light" style="background-color: #e3f2fd;">
  <!-- Navbar content -->
</nav>

容器

虽然它不是必需的，但您可以将导航栏包裹在 a.container中以使其在页面上居中 - 尽管请注意仍然需要内部容器。或者，您可以在内添加一个容器，以仅将固定或静态顶部导航栏.navbar的内容居中。

<div class="container">
  <nav class="navbar navbar-expand-lg navbar-light bg-light">
    <div class="container-fluid">
      <a class="navbar-brand" href="#">Navbar</a>
    </div>
  </nav>
</div>

使用任何响应式容器来更改导航栏中内容的显示宽度。

<nav class="navbar navbar-expand-lg navbar-light bg-light">
  <div class="container-md">
    <a class="navbar-brand" href="#">Navbar</a>
  </div>
</nav>

放置

使用我们的位置实用程序将导航栏放置在非静态位置。选择固定到顶部、固定到底部或粘到顶部（随页面滚动，直到它到达顶部，然后停留在那里）。固定导航栏使用position: fixed，这意味着它们是从 DOM 的正常流程中拉出的，并且可能需要自定义 CSS（例如，padding-top在上<body>）以防止与其他元素重叠。

另请注意，并不是每个浏览器都完全支持.sticky-top使用position: sticky。

<nav class="navbar navbar-light bg-light">
  <div class="container-fluid">
    <a class="navbar-brand" href="#">Default</a>
  </div>
</nav>

<nav class="navbar fixed-top navbar-light bg-light">
  <div class="container-fluid">
    <a class="navbar-brand" href="#">Fixed top</a>
  </div>
</nav>

<nav class="navbar fixed-bottom navbar-light bg-light">
  <div class="container-fluid">
    <a class="navbar-brand" href="#">Fixed bottom</a>
  </div>
</nav>

<nav class="navbar sticky-top navbar-light bg-light">
  <div class="container-fluid">
    <a class="navbar-brand" href="#">Sticky top</a>
  </div>
</nav>

滚动

添加.navbar-nav-scroll到.navbar-nav（或其他导航栏子组件）以在折叠导航栏的可切换内容中启用垂直滚动。默认情况下，滚动开始于75vh（或视口高度的 75%），但您可以使用本地 CSS 自定义属性--bs-navbar-height或自定义样式覆盖它。当导航栏展开时，在较大的视口中，内容将像在默认导航栏中一样显示。

请注意，这种行为有一个潜在的缺点，即overflow设置overflow-y: auto时（需要在此处滚动内容），overflow-x相当于auto，它将裁剪一些水平内容。

.navbar-nav-scroll这是一个使用with的示例导航栏style="--bs-scroll-height: 100px;"，带有一些额外的边距实用程序以获得最佳间距。

<nav class="navbar navbar-expand-lg navbar-light bg-light">
  <div class="container-fluid">
    <a class="navbar-brand" href="#">Navbar scroll</a>
    <button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#navbarScroll" aria-controls="navbarScroll" aria-expanded="false" aria-label="Toggle navigation">
      <span class="navbar-toggler-icon"></span>
    </button>
    <div class="collapse navbar-collapse" id="navbarScroll">
      <ul class="navbar-nav me-auto my-2 my-lg-0 navbar-nav-scroll" style="--bs-scroll-height: 100px;">
        <li class="nav-item">
          <a class="nav-link active" aria-current="page" href="#">Home</a>
        </li>
        <li class="nav-item">
          <a class="nav-link" href="#">Link</a>
        </li>
        <li class="nav-item dropdown">
          <a class="nav-link dropdown-toggle" href="#" id="navbarScrollingDropdown" role="button" data-bs-toggle="dropdown" aria-expanded="false">
            Link
          </a>
          <ul class="dropdown-menu" aria-labelledby="navbarScrollingDropdown">
            <li><a class="dropdown-item" href="#">Action</a></li>
            <li><a class="dropdown-item" href="#">Another action</a></li>
            <li><hr class="dropdown-divider"></li>
            <li><a class="dropdown-item" href="#">Something else here</a></li>
          </ul>
        </li>
        <li class="nav-item">
          <a class="nav-link disabled">Link</a>
        </li>
      </ul>
      <form class="d-flex">
        <input class="form-control me-2" type="search" placeholder="Search" aria-label="Search">
        <button class="btn btn-outline-success" type="submit">Search</button>
      </form>
    </div>
  </div>
</nav>

响应行为

导航栏可以使用.navbar-toggler、.navbar-collapse和.navbar-expand{-sm|-md|-lg|-xl|-xxl}类来确定其内容何时折叠在按钮后面。结合其他实用程序，您可以轻松选择何时显示或隐藏特定元素。

对于从不折叠.navbar-expand的导航栏，在导航栏上添加类。对于总是折叠的导航栏，不要添加任何.navbar-expand类。

切换器

导航栏切换器默认是左对齐的，但是如果它们跟随像 a 这样的兄弟元素.navbar-brand，它们会自动对齐到最右边。反转标记将反转切换器的位置。以下是不同切换样式的示例。

.navbar-brand在最小断点处没有显示：

<nav class="navbar navbar-expand-lg navbar-light bg-light">
  <div class="container-fluid">
    <button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#navbarTogglerDemo01" aria-controls="navbarTogglerDemo01" aria-expanded="false" aria-label="Toggle navigation">
      <span class="navbar-toggler-icon"></span>
    </button>
    <div class="collapse navbar-collapse" id="navbarTogglerDemo01">
      <a class="navbar-brand" href="#">Hidden brand</a>
      <ul class="navbar-nav me-auto mb-2 mb-lg-0">
        <li class="nav-item">
          <a class="nav-link active" aria-current="page" href="#">Home</a>
        </li>
        <li class="nav-item">
          <a class="nav-link" href="#">Link</a>
        </li>
        <li class="nav-item">
          <a class="nav-link disabled">Disabled</a>
        </li>
      </ul>
      <form class="d-flex">
        <input class="form-control me-2" type="search" placeholder="Search" aria-label="Search">
        <button class="btn btn-outline-success" type="submit">Search</button>
      </form>
    </div>
  </div>
</nav>

左侧显示品牌名称，右侧显示切换器：

<nav class="navbar navbar-expand-lg navbar-light bg-light">
  <div class="container-fluid">
    <a class="navbar-brand" href="#">Navbar</a>
    <button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#navbarTogglerDemo02" aria-controls="navbarTogglerDemo02" aria-expanded="false" aria-label="Toggle navigation">
      <span class="navbar-toggler-icon"></span>
    </button>
    <div class="collapse navbar-collapse" id="navbarTogglerDemo02">
      <ul class="navbar-nav me-auto mb-2 mb-lg-0">
        <li class="nav-item">
          <a class="nav-link active" aria-current="page" href="#">Home</a>
        </li>
        <li class="nav-item">
          <a class="nav-link" href="#">Link</a>
        </li>
        <li class="nav-item">
          <a class="nav-link disabled">Disabled</a>
        </li>
      </ul>
      <form class="d-flex">
        <input class="form-control me-2" type="search" placeholder="Search" aria-label="Search">
        <button class="btn btn-outline-success" type="submit">Search</button>
      </form>
    </div>
  </div>
</nav>

左侧是切换器，右侧是品牌名称：

<nav class="navbar navbar-expand-lg navbar-light bg-light">
  <div class="container-fluid">
    <button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#navbarTogglerDemo03" aria-controls="navbarTogglerDemo03" aria-expanded="false" aria-label="Toggle navigation">
      <span class="navbar-toggler-icon"></span>
    </button>
    <a class="navbar-brand" href="#">Navbar</a>
    <div class="collapse navbar-collapse" id="navbarTogglerDemo03">
      <ul class="navbar-nav me-auto mb-2 mb-lg-0">
        <li class="nav-item">
          <a class="nav-link active" aria-current="page" href="#">Home</a>
        </li>
        <li class="nav-item">
          <a class="nav-link" href="#">Link</a>
        </li>
        <li class="nav-item">
          <a class="nav-link disabled">Disabled</a>
        </li>
      </ul>
      <form class="d-flex">
        <input class="form-control me-2" type="search" placeholder="Search" aria-label="Search">
        <button class="btn btn-outline-success" type="submit">Search</button>
      </form>
    </div>
  </div>
</nav>

外部内容

有时您想使用折叠插件来触发结构上位于.navbar. 因为我们的插件适用于id和data-bs-target匹配，所以很容易做到！

Collapsed content

Toggleable via the navbar brand.

<div class="collapse" id="navbarToggleExternalContent">
  <div class="bg-dark p-4">
    <h5 class="text-white h4">Collapsed content</h5>
    <span class="text-muted">Toggleable via the navbar brand.</span>
  </div>
</div>
<nav class="navbar navbar-dark bg-dark">
  <div class="container-fluid">
    <button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#navbarToggleExternalContent" aria-controls="navbarToggleExternalContent" aria-expanded="false" aria-label="Toggle navigation">
      <span class="navbar-toggler-icon"></span>
    </button>
  </div>
</nav>

执行此操作时，我们建议您添加额外的 JavaScript，以便在容器打开时以编程方式将焦点移至容器。否则，键盘用户和辅助技术用户可能很难找到新显示的内容 - 特别是如果打开的容器位于文档结构中的切换器之前。我们还建议确保切换器具有aria-controls指向id内容容器的属性。理论上，这允许辅助技术用户直接从切换器跳转到它控制的容器——但目前对此的支持相当不完整。

画布外

使用 offcanvas 插件将您的展开和折叠导航栏转换为 offcanvas 抽屉。我们扩展了 offcanvas 默认样式并使用我们的.navbar-expand-*类来创建动态和灵活的导航侧边栏。

在下面的示例中，要创建一个始终跨所有断点折叠的 offcanvas 导航栏，请.navbar-expand-*完全省略该类。

<nav class="navbar navbar-light bg-light fixed-top">
  <div class="container-fluid">
    <a class="navbar-brand" href="#">Offcanvas navbar</a>
    <button class="navbar-toggler" type="button" data-bs-toggle="offcanvas" data-bs-target="#offcanvasNavbar" aria-controls="offcanvasNavbar">
      <span class="navbar-toggler-icon"></span>
    </button>
    <div class="offcanvas offcanvas-end" tabindex="-1" id="offcanvasNavbar" aria-labelledby="offcanvasNavbarLabel">
      <div class="offcanvas-header">
        <h5 class="offcanvas-title" id="offcanvasNavbarLabel">Offcanvas</h5>
        <button type="button" class="btn-close text-reset" data-bs-dismiss="offcanvas" aria-label="Close"></button>
      </div>
      <div class="offcanvas-body">
        <ul class="navbar-nav justify-content-end flex-grow-1 pe-3">
          <li class="nav-item">
            <a class="nav-link active" aria-current="page" href="#">Home</a>
          </li>
          <li class="nav-item">
            <a class="nav-link" href="#">Link</a>
          </li>
          <li class="nav-item dropdown">
            <a class="nav-link dropdown-toggle" href="#" id="offcanvasNavbarDropdown" role="button" data-bs-toggle="dropdown" aria-expanded="false">
              Dropdown
            </a>
            <ul class="dropdown-menu" aria-labelledby="offcanvasNavbarDropdown">
              <li><a class="dropdown-item" href="#">Action</a></li>
              <li><a class="dropdown-item" href="#">Another action</a></li>
              <li>
                <hr class="dropdown-divider">
              </li>
              <li><a class="dropdown-item" href="#">Something else here</a></li>
            </ul>
          </li>
        </ul>
        <form class="d-flex">
          <input class="form-control me-2" type="search" placeholder="Search" aria-label="Search">
          <button class="btn btn-outline-success" type="submit">Search</button>
        </form>
      </div>
    </div>
  </div>
</nav>

要创建一个在特定断点处扩展为普通导航栏的 offcanvas 导航栏lg，请使用.navbar-expand-lg.

<nav class="navbar navbar-light navbar-expand-lg bg-light fixed-top">
  <a class="navbar-brand" href="#">Offcanvas navbar</a>
  <button class="navbar-toggler" type="button" data-bs-toggle="offcanvas" data-bs-target="#navbarOffcanvasLg" aria-controls="navbarOffcanvasLg">
    <span class="navbar-toggler-icon"></span>
  </button>
  <div class="offcanvas offcanvas-end" tabindex="-1" id="navbarOffcanvasLg" aria-labelledby="navbarOffcanvasLgLabel">
    ...
  </div>
</nav>

萨斯

变量

$navbar-padding-y:                  $spacer * .5;
$navbar-padding-x:                  null;

$navbar-nav-link-padding-x:         .5rem;

$navbar-brand-font-size:            $font-size-lg;
// Compute the navbar-brand padding-y so the navbar-brand will have the same height as navbar-text and nav-link
$nav-link-height:                   $font-size-base * $line-height-base + $nav-link-padding-y * 2;
$navbar-brand-height:               $navbar-brand-font-size * $line-height-base;
$navbar-brand-padding-y:            ($nav-link-height - $navbar-brand-height) * .5;
$navbar-brand-margin-end:           1rem;

$navbar-toggler-padding-y:          .25rem;
$navbar-toggler-padding-x:          .75rem;
$navbar-toggler-font-size:          $font-size-lg;
$navbar-toggler-border-radius:      $btn-border-radius;
$navbar-toggler-focus-width:        $btn-focus-width;
$navbar-toggler-transition:         box-shadow .15s ease-in-out;

$navbar-dark-color:                 rgba($white, .55);
$navbar-dark-hover-color:           rgba($white, .75);
$navbar-dark-active-color:          $white;
$navbar-dark-disabled-color:        rgba($white, .25);
$navbar-dark-toggler-icon-bg:       url("data:image/svg+xml,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 30 30'><path stroke='#{$navbar-dark-color}' stroke-linecap='round' stroke-miterlimit='10' stroke-width='2' d='M4 7h22M4 15h22M4 23h22'/></svg>");
$navbar-dark-toggler-border-color:  rgba($white, .1);

$navbar-light-color:                rgba($black, .55);
$navbar-light-hover-color:          rgba($black, .7);
$navbar-light-active-color:         rgba($black, .9);
$navbar-light-disabled-color:       rgba($black, .3);
$navbar-light-toggler-icon-bg:      url("data:image/svg+xml,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 30 30'><path stroke='#{$navbar-light-color}' stroke-linecap='round' stroke-miterlimit='10' stroke-width='2' d='M4 7h22M4 15h22M4 23h22'/></svg>");
$navbar-light-toggler-border-color: rgba($black, .1);

$navbar-light-brand-color:                $navbar-light-active-color;
$navbar-light-brand-hover-color:          $navbar-light-active-color;
$navbar-dark-brand-color:                 $navbar-dark-active-color;
$navbar-dark-brand-hover-color:           $navbar-dark-active-color;

环形

响应式导航栏展开/折叠类（例如.navbar-expand-lg）与$breakpoints地图组合并通过scss/_navbar.scss.

// Generate series of `.navbar-expand-*` responsive classes for configuring
// where your navbar collapses.
.navbar-expand {
  @each $breakpoint in map-keys($grid-breakpoints) {
    $next: breakpoint-next($breakpoint, $grid-breakpoints);
    $infix: breakpoint-infix($next, $grid-breakpoints);

    // stylelint-disable-next-line scss/selector-no-union-class-name
    &#{$infix} {
      @include media-breakpoint-up($next) {
        flex-wrap: nowrap;
        justify-content: flex-start;

        .navbar-nav {
          flex-direction: row;

          .dropdown-menu {
            position: absolute;
          }

          .nav-link {
            padding-right: $navbar-nav-link-padding-x;
            padding-left: $navbar-nav-link-padding-x;
          }
        }

        .navbar-nav-scroll {
          overflow: visible;
        }

        .navbar-collapse {
          display: flex !important; // stylelint-disable-line declaration-no-important
          flex-basis: auto;
        }

        .navbar-toggler {
          display: none;
        }

        .offcanvas-header {
          display: none;
        }

        .offcanvas {
          position: inherit;
          bottom: 0;
          z-index: 1000;
          flex-grow: 1;
          visibility: visible !important; // stylelint-disable-line declaration-no-important
          background-color: transparent;
          border-right: 0;
          border-left: 0;
          @include transition(none);
          transform: none;
        }
        .offcanvas-top,
        .offcanvas-bottom {
          height: auto;
          border-top: 0;
          border-bottom: 0;
        }

        .offcanvas-body {
          display: flex;
          flex-grow: 0;
          padding: 0;
          overflow-y: visible;
        }
      }
    }
  }
}