導覽列(Navbar)
Bootstrap 強大、響應式導覽標題元件——導覽列的文件與範例。包含品牌、導覽等支援,以及我們的摺疊外掛程式支援。
運作原理(How it works)
在開始使用導覽列之前,您需要了解以下內容:
- 導覽列需要一個包裹的
.navbar,並搭配.navbar-expand{-sm|-md|-lg|-xl|-xxl}來實現響應式摺疊,以及色彩配置類別。 - 導覽列及其內容預設為流體佈局。變更容器以不同方式限制其水平寬度。
- 使用我們的間距和 Flexbox 通用類別來控制導覽列內的間距和對齊。
- 導覽列預設為響應式,但您可以輕鬆修改來變更這一點。響應式行為依賴我們的 Collapse JavaScript 外掛程式。
- 透過使用
<nav>元素來確保無障礙性,或者如果使用更通用的元素如<div>,請在每個導覽列上加入role="navigation",以明確將其標識為輔助技術使用者的地標區域。 - 使用
aria-current="page"表示當前頁面,或使用aria-current="true"表示集合中的當前項目。 - v5.2.0 新功能: 導覽列可以使用範圍限於
.navbar基礎類別的 CSS 變數來設定主題。.navbar-light已被棄用,.navbar-dark已重寫為覆寫 CSS 變數而非加入額外樣式。
此元件的動畫效果取決於 prefers-reduced-motion 媒體查詢。請參閱我們無障礙文件中的減少動態效果章節。
支援的內容(Supported content)
導覽列內建支援多種子元件。根據需要從以下選項中選擇:
.navbar-brand用於您的公司、產品或專案名稱。.navbar-nav用於全高度且輕量的導覽(包含下拉選單支援)。.navbar-toggler用於搭配我們的摺疊外掛程式和其他導覽切換行為。- Flexbox 和間距通用類別用於任何表單控制項和動作。
.navbar-text用於加入垂直置中的文字字串。.collapse.navbar-collapse用於依據父元素中斷點分組和隱藏導覽列內容。- 加入可選的
.navbar-nav-scroll來設定max-height並捲動展開的導覽列內容。
以下是一個響應式淺色主題導覽列的範例,包含所有子元件,會在 lg(大型)中斷點自動摺疊。
<nav class="navbar navbar-expand-lg bg-body-tertiary">
<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="#" role="button" data-bs-toggle="dropdown" aria-expanded="false">
Dropdown
</a>
<ul class="dropdown-menu">
<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" aria-disabled="true">Disabled</a>
</li>
</ul>
<form class="d-flex" role="search">
<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> 此範例使用背景(bg-body-tertiary)和間距(me-auto、mb-2、mb-lg-0、me-2)通用類別。
品牌(Brand)
.navbar-brand 可以套用到大多數元素,但錨點效果最佳,因為某些元素可能需要通用類別或自訂樣式。
文字(Text)
在帶有 .navbar-brand 類別的元素中加入您的文字。
<!-- As a link -->
<nav class="navbar bg-body-tertiary">
<div class="container-fluid">
<a class="navbar-brand" href="#">Navbar</a>
</div>
</nav>
<!-- As a heading -->
<nav class="navbar bg-body-tertiary">
<div class="container-fluid">
<span class="navbar-brand mb-0 h1">Navbar</span>
</div>
</nav> 圖片(Image)
您可以將 .navbar-brand 內的文字替換為 <img>。
<nav class="navbar bg-body-tertiary">
<div class="container">
<a class="navbar-brand" href="#">
<img src="/docs/5.3/assets/brand/bootstrap-logo.svg" alt="Bootstrap" width="30" height="24">
</a>
</div>
</nav> 圖片和文字(Image and text)
您也可以使用一些額外的通用類別同時加入圖片和文字。請注意在 <img> 上加入了 .d-inline-block 和 .align-text-top。
<nav class="navbar bg-body-tertiary">
<div class="container-fluid">
<a class="navbar-brand" href="#">
<img src="/docs/5.3/assets/brand/bootstrap-logo.svg" alt="Logo" width="30" height="24" class="d-inline-block align-text-top">
Bootstrap
</a>
</div>
</nav> 導覽(Nav)
導覽列的導覽連結建構於我們的 .nav 選項之上,並具有自己的修飾類別,需要使用切換器類別來實現適當的響應式樣式。導覽列中的導覽也會擴展以佔據盡可能多的水平空間,以確保您的導覽列內容正確對齊。
在 .nav-link 上加入 .active 類別來表示當前頁面。
請注意,您還應該在啟用的 .nav-link 上加入 aria-current 屬性。
<nav class="navbar navbar-expand-lg bg-body-tertiary">
<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" aria-disabled="true">Disabled</a>
</li>
</ul>
</div>
</div>
</nav> 而且由於我們使用類別來建立導覽,如果您願意,可以完全避免使用列表的方式。
<nav class="navbar navbar-expand-lg bg-body-tertiary">
<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" aria-disabled="true">Disabled</a>
</div>
</div>
</div>
</nav> 您也可以在導覽列中使用下拉選單。下拉選單需要一個包裹元素來定位,因此請確保為 .nav-item 和 .nav-link 使用獨立且巢狀的元素,如下所示。
<nav class="navbar navbar-expand-lg bg-body-tertiary">
<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="#" role="button" data-bs-toggle="dropdown" aria-expanded="false">
Dropdown link
</a>
<ul class="dropdown-menu">
<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> 表單(Forms)
在導覽列中放置各種表單控制項和元件:
<nav class="navbar bg-body-tertiary">
<div class="container-fluid">
<form class="d-flex" role="search">
<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 的直接子元素使用 Flexbox 佈局,並預設為 justify-content: space-between。根據需要使用額外的 Flexbox 通用類別來調整此行為。
<nav class="navbar bg-body-tertiary">
<div class="container-fluid">
<a class="navbar-brand">Navbar</a>
<form class="d-flex" role="search">
<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> 輸入群組也可以使用。如果您的導覽列是一個完整的表單,或主要是表單,您可以使用 <form> 元素作為容器並節省一些 HTML。
<nav class="navbar bg-body-tertiary">
<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> 各種按鈕也可作為這些導覽列表單的一部分。這也是一個很好的提醒,垂直對齊通用類別可用於對齊不同大小的元素。
<nav class="navbar bg-body-tertiary">
<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> 文字(Text)
導覽列可以透過 .navbar-text 包含一些文字。此類別調整文字字串的垂直對齊和水平間距。
<nav class="navbar bg-body-tertiary">
<div class="container-fluid">
<span class="navbar-text">
Navbar text with an inline element
</span>
</div>
</nav> 根據需要與其他元件和通用類別混合搭配。
<nav class="navbar navbar-expand-lg bg-body-tertiary">
<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> 色彩配置(Color schemes)
v5.3.0 的新深色導覽列 — 我們已棄用 .navbar-dark,改用新的 data-bs-theme="dark"。在 .navbar 上加入 data-bs-theme="dark" 以啟用元件特定的色彩模式。了解更多關於我們的色彩模式。
v5.2.0 新功能 — 導覽列主題現在由 CSS 變數驅動,.navbar-light 已被棄用。CSS 變數套用於 .navbar,預設為「淺色」外觀,可透過 .navbar-dark 覆寫。
由於 Bootstrap 結合了 Sass 和 CSS 變數,導覽列主題比以往更容易。預設是我們用於淺色背景色的「淺色導覽列」,但您也可以在 .navbar 父元素上套用 data-bs-theme="dark" 以使用深色背景色。然後,使用 .bg-* 和額外的通用類別進行自訂。
<nav class="navbar bg-dark border-bottom border-body" data-bs-theme="dark">
<!-- Navbar content -->
</nav>
<nav class="navbar bg-primary" data-bs-theme="dark">
<!-- Navbar content -->
</nav>
<nav class="navbar" style="background-color: #e3f2fd;" data-bs-theme="light">
<!-- Navbar content -->
</nav>
容器(Containers)
雖然不是必需的,您可以將導覽列包裹在 .container 中以使其在頁面上置中——但請注意,仍需要一個內部容器。或者您可以在 .navbar 內部加入容器,僅將固定或靜態頂部導覽列的內容置中。
<div class="container">
<nav class="navbar navbar-expand-lg bg-body-tertiary">
<div class="container-fluid">
<a class="navbar-brand" href="#">Navbar</a>
</div>
</nav>
</div> 使用任何響應式容器來改變導覽列內容的寬度呈現方式。
<nav class="navbar navbar-expand-lg bg-body-tertiary">
<div class="container-md">
<a class="navbar-brand" href="#">Navbar</a>
</div>
</nav> 位置(Placement)
使用我們的定位通用類別將導覽列放置在非靜態位置。從固定在頂部、固定在底部、黏著在頂部(隨頁面捲動直到到達頂部,然後停留在那裡)或黏著在底部(隨頁面捲動直到到達底部,然後停留在那裡)中選擇。
固定導覽列使用 position: fixed,這意味著它們會從 DOM 的正常流程中拉出,可能需要自訂 CSS(例如,在 <body> 上加入 padding-top)來防止與其他元素重疊。
<nav class="navbar bg-body-tertiary">
<div class="container-fluid">
<a class="navbar-brand" href="#">Default</a>
</div>
</nav> <nav class="navbar fixed-top bg-body-tertiary">
<div class="container-fluid">
<a class="navbar-brand" href="#">Fixed top</a>
</div>
</nav> <nav class="navbar fixed-bottom bg-body-tertiary">
<div class="container-fluid">
<a class="navbar-brand" href="#">Fixed bottom</a>
</div>
</nav> <nav class="navbar sticky-top bg-body-tertiary">
<div class="container-fluid">
<a class="navbar-brand" href="#">Sticky top</a>
</div>
</nav> <nav class="navbar sticky-bottom bg-body-tertiary">
<div class="container-fluid">
<a class="navbar-brand" href="#">Sticky bottom</a>
</div>
</nav> 捲動(Scrolling)
在 .navbar-nav(或其他導覽列子元件)上加入 .navbar-nav-scroll,以在摺疊導覽列的可切換內容中啟用垂直捲動。預設情況下,捲動在 75vh(或視窗高度的 75%)時啟動,但您可以使用區域 CSS 自訂屬性 --bs-navbar-height 或自訂樣式覆寫它。在較大的視窗中,當導覽列展開時,內容會如預設導覽列中一樣顯示。
請注意,此行為有一個潛在的 overflow 缺點——當設定 overflow-y: auto(此處捲動內容所需)時,overflow-x 等同於 auto,這會裁切一些水平內容。
以下是使用 .navbar-nav-scroll 搭配 style="--bs-scroll-height: 100px;" 的導覽列範例,並使用一些額外的外距通用類別來獲得最佳間距。
<nav class="navbar navbar-expand-lg bg-body-tertiary">
<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="#" role="button" data-bs-toggle="dropdown" aria-expanded="false">
Link
</a>
<ul class="dropdown-menu">
<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" aria-disabled="true">Link</a>
</li>
</ul>
<form class="d-flex" role="search">
<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> 響應式行為(Responsive behaviors)
導覽列可以使用 .navbar-toggler、.navbar-collapse 和 .navbar-expand{-sm|-md|-lg|-xl|-xxl} 類別來決定何時將內容摺疊到按鈕後面。結合其他通用類別,您可以輕鬆選擇何時顯示或隱藏特定元素。
對於永不摺疊的導覽列,在導覽列上加入 .navbar-expand 類別。對於始終摺疊的導覽列,不要加入任何 .navbar-expand 類別。
切換器(Toggler)
導覽列切換器預設靠左對齊,但如果它們跟隨像 .navbar-brand 這樣的兄弟元素,它們會自動對齊到最右側。顛倒您的標記會顛倒切換器的位置。以下是不同切換樣式的範例。
在最小中斷點時不顯示 .navbar-brand:
<nav class="navbar navbar-expand-lg bg-body-tertiary">
<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" aria-disabled="true">Disabled</a>
</li>
</ul>
<form class="d-flex" role="search">
<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> 品牌名稱在左側,切換器在右側:
<nav class="navbar navbar-expand-lg bg-body-tertiary">
<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" aria-disabled="true">Disabled</a>
</li>
</ul>
<form class="d-flex" role="search">
<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> 切換器在左側,品牌名稱在右側:
<nav class="navbar navbar-expand-lg bg-body-tertiary">
<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" aria-disabled="true">Disabled</a>
</li>
</ul>
<form class="d-flex" role="search">
<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> 外部內容(External content)
有時您希望使用摺疊外掛程式來觸發結構上位於 .navbar 外部的內容容器元素。因為我們的外掛程式是透過 id 和 data-bs-target 匹配來運作的,這很容易做到!
<div class="collapse" id="navbarToggleExternalContent" data-bs-theme="dark">
<div class="bg-dark p-4">
<h5 class="text-body-emphasis h4">Collapsed content</h5>
<span class="text-body-secondary">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> 當您這樣做時,我們建議加入額外的 JavaScript,在容器開啟時以程式方式將焦點移動到容器。否則,鍵盤使用者和輔助技術使用者可能很難找到新顯示的內容——特別是如果開啟的容器在文件結構中位於切換器之前。我們還建議確保切換器具有 aria-controls 屬性,指向內容容器的 id。理論上,這允許輔助技術使用者直接從切換器跳到它控制的容器——但目前對此的支援相當不完整。
側邊面板(Offcanvas)
使用側邊面板元件將您的展開和摺疊導覽列轉換為側邊面板抽屜。我們同時擴展側邊面板的預設樣式並使用我們的 .navbar-expand-* 類別來建立動態且靈活的導覽側邊欄。
在下面的範例中,若要建立在所有中斷點都始終摺疊的側邊面板導覽列,請完全省略 .navbar-expand-* 類別。
<nav class="navbar bg-body-tertiary 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" aria-label="Toggle navigation">
<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" 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="#" role="button" data-bs-toggle="dropdown" aria-expanded="false">
Dropdown
</a>
<ul class="dropdown-menu">
<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 mt-3" role="search">
<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> 若要建立在特定中斷點(如 lg)展開為正常導覽列的側邊面板導覽列,請使用 .navbar-expand-lg。
<nav class="navbar navbar-expand-lg bg-body-tertiary 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" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="offcanvas offcanvas-end" tabindex="-1" id="navbarOffcanvasLg" aria-labelledby="navbarOffcanvasLgLabel">
...
</div>
</nav>
在深色導覽列中使用側邊面板時,請注意您可能需要在側邊面板內容上設定深色背景,以避免文字變得難以辨認。在下面的範例中,我們在 .navbar 上加入 .navbar-dark 和 .bg-dark,在 .offcanvas 上加入 .text-bg-dark,在 .dropdown-menu 上加入 .dropdown-menu-dark,在 .btn-close 上加入 .btn-close-white,以便在深色側邊面板中正確設定樣式。
<nav class="navbar navbar-dark bg-dark fixed-top">
<div class="container-fluid">
<a class="navbar-brand" href="#">Offcanvas dark navbar</a>
<button class="navbar-toggler" type="button" data-bs-toggle="offcanvas" data-bs-target="#offcanvasDarkNavbar" aria-controls="offcanvasDarkNavbar" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="offcanvas offcanvas-end text-bg-dark" tabindex="-1" id="offcanvasDarkNavbar" aria-labelledby="offcanvasDarkNavbarLabel">
<div class="offcanvas-header">
<h5 class="offcanvas-title" id="offcanvasDarkNavbarLabel">Dark offcanvas</h5>
<button type="button" class="btn-close btn-close-white" 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="#" role="button" data-bs-toggle="dropdown" aria-expanded="false">
Dropdown
</a>
<ul class="dropdown-menu dropdown-menu-dark">
<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 mt-3" role="search">
<input class="form-control me-2" type="search" placeholder="Search" aria-label="Search"/>
<button class="btn btn-success" type="submit">Search</button>
</form>
</div>
</div>
</div>
</nav> CSS
變數(Variables)
Added in v5.2.0作為 Bootstrap 不斷發展的 CSS 變數方法的一部分,導覽列現在在 .navbar 上使用區域 CSS 變數來增強即時自訂功能。CSS 變數的值是透過 Sass 設定的,因此仍然支援 Sass 自訂。
--#{$prefix}navbar-padding-x: #{if($navbar-padding-x == null, 0, $navbar-padding-x)};
--#{$prefix}navbar-padding-y: #{$navbar-padding-y};
--#{$prefix}navbar-color: #{$navbar-light-color};
--#{$prefix}navbar-hover-color: #{$navbar-light-hover-color};
--#{$prefix}navbar-disabled-color: #{$navbar-light-disabled-color};
--#{$prefix}navbar-active-color: #{$navbar-light-active-color};
--#{$prefix}navbar-brand-padding-y: #{$navbar-brand-padding-y};
--#{$prefix}navbar-brand-margin-end: #{$navbar-brand-margin-end};
--#{$prefix}navbar-brand-font-size: #{$navbar-brand-font-size};
--#{$prefix}navbar-brand-color: #{$navbar-light-brand-color};
--#{$prefix}navbar-brand-hover-color: #{$navbar-light-brand-hover-color};
--#{$prefix}navbar-nav-link-padding-x: #{$navbar-nav-link-padding-x};
--#{$prefix}navbar-toggler-padding-y: #{$navbar-toggler-padding-y};
--#{$prefix}navbar-toggler-padding-x: #{$navbar-toggler-padding-x};
--#{$prefix}navbar-toggler-font-size: #{$navbar-toggler-font-size};
--#{$prefix}navbar-toggler-icon-bg: #{escape-svg($navbar-light-toggler-icon-bg)};
--#{$prefix}navbar-toggler-border-color: #{$navbar-light-toggler-border-color};
--#{$prefix}navbar-toggler-border-radius: #{$navbar-toggler-border-radius};
--#{$prefix}navbar-toggler-focus-width: #{$navbar-toggler-focus-width};
--#{$prefix}navbar-toggler-transition: #{$navbar-toggler-transition};
.navbar-nav 上也存在一些額外的 CSS 變數:
--#{$prefix}nav-link-padding-x: 0;
--#{$prefix}nav-link-padding-y: #{$nav-link-padding-y};
@include rfs($nav-link-font-size, --#{$prefix}nav-link-font-size);
--#{$prefix}nav-link-font-weight: #{$nav-link-font-weight};
--#{$prefix}nav-link-color: var(--#{$prefix}navbar-color);
--#{$prefix}nav-link-hover-color: var(--#{$prefix}navbar-hover-color);
--#{$prefix}nav-link-disabled-color: var(--#{$prefix}navbar-disabled-color);
透過 CSS 變數進行自訂可以在 .navbar-dark 類別中看到,我們在不加入重複 CSS 選擇器的情況下覆寫特定值。
--#{$prefix}navbar-color: #{$navbar-dark-color};
--#{$prefix}navbar-hover-color: #{$navbar-dark-hover-color};
--#{$prefix}navbar-disabled-color: #{$navbar-dark-disabled-color};
--#{$prefix}navbar-active-color: #{$navbar-dark-active-color};
--#{$prefix}navbar-brand-color: #{$navbar-dark-brand-color};
--#{$prefix}navbar-brand-hover-color: #{$navbar-dark-brand-hover-color};
--#{$prefix}navbar-toggler-border-color: #{$navbar-dark-toggler-border-color};
--#{$prefix}navbar-toggler-icon-bg: #{escape-svg($navbar-dark-toggler-icon-bg)};
Sass 變數(Sass variables)
所有導覽列的變數:
$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;
$navbar-light-color: rgba(var(--#{$prefix}emphasis-color-rgb), .65);
$navbar-light-hover-color: rgba(var(--#{$prefix}emphasis-color-rgb), .8);
$navbar-light-active-color: rgba(var(--#{$prefix}emphasis-color-rgb), 1);
$navbar-light-disabled-color: rgba(var(--#{$prefix}emphasis-color-rgb), .3);
$navbar-light-icon-color: rgba($body-color, .75);
$navbar-light-toggler-icon-bg: url("data:image/svg+xml,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 30 30'><path stroke='#{$navbar-light-icon-color}' stroke-linecap='round' stroke-miterlimit='10' stroke-width='2' d='M4 7h22M4 15h22M4 23h22'/></svg>");
$navbar-light-toggler-border-color: rgba(var(--#{$prefix}emphasis-color-rgb), .15);
$navbar-light-brand-color: $navbar-light-active-color;
$navbar-light-brand-hover-color: $navbar-light-active-color;
深色導覽列的變數:
$navbar-dark-color: rgba($white, .55);
$navbar-dark-hover-color: rgba($white, .75);
$navbar-dark-active-color: $white;
$navbar-dark-disabled-color: rgba($white, .25);
$navbar-dark-icon-color: $navbar-dark-color;
$navbar-dark-toggler-icon-bg: url("data:image/svg+xml,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 30 30'><path stroke='#{$navbar-dark-icon-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-dark-brand-color: $navbar-dark-active-color;
$navbar-dark-brand-hover-color: $navbar-dark-active-color;
Sass 迴圈(Sass loops)
響應式導覽列展開/摺疊類別(例如 .navbar-expand-lg)與 $breakpoints 映射結合,並透過 scss/_navbar.scss 中的迴圈產生。
// 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($next) {
flex-wrap: nowrap;
justify-content: flex-start;
.navbar-nav {
flex-direction: row;
.dropdown-menu {
position: absolute;
}
.nav-link {
padding-right: var(--#{$prefix}navbar-nav-link-padding-x);
padding-left: var(--#{$prefix}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 {
// stylelint-disable declaration-no-important
position: static;
z-index: auto;
flex-grow: 1;
width: auto !important;
height: auto !important;
visibility: visible !important;
background-color: transparent !important;
border: 0 !important;
transform: none !important;
@include box-shadow(none);
@include transition(none);
// stylelint-enable declaration-no-important
.offcanvas-header {
display: none;
}
.offcanvas-body {
display: flex;
flex-grow: 0;
padding: 0;
overflow-y: visible;
}
}
}
}
}
}