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flexbox 通用類別的套件包管理網格欄的排版、對齊、尺寸縮放,以及導覽、元件等。對於更複雜的表現則需要自訂 CSS。

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啟用 flex

使用 display 通用類別來創建一個 flexbox 容器,並將 直屬的子元素 轉換為 flex 屬性。增加額外的 flex 屬性,也能夠進一步修改 flex 容器和屬性。

I'm a flexbox container!
<div class="d-flex p-2 bd-highlight">I'm a flexbox container!</div>
I'm an inline flexbox container!
<div class="d-inline-flex p-2 bd-highlight">I'm an inline flexbox container!</div>

.d-flex.d-inline-flex 也包含響應式的變化。

  • .d-flex
  • .d-inline-flex
  • .d-sm-flex
  • .d-sm-inline-flex
  • .d-md-flex
  • .d-md-inline-flex
  • .d-lg-flex
  • .d-lg-inline-flex
  • .d-xl-flex
  • .d-xl-inline-flex
  • .d-xxl-flex
  • .d-xxl-inline-flex

方向性

透過通用類別來設定 flex 容器與內層 flex 的方向,在大多的情況下你可以忽略水平的 class,因為瀏覽器預設值是 row。不過有些特定情境下需要特別設定這個值(像是響應式情境)。

使用 .flex-row 來設定水平的方向(瀏覽器預設值),或是使用 .flex-row-reverse 來作水平方向的反轉。

Flex item 1
Flex item 2
Flex item 3
Flex item 1
Flex item 2
Flex item 3
<div class="d-flex flex-row bd-highlight mb-3">
  <div class="p-2 bd-highlight">Flex item 1</div>
  <div class="p-2 bd-highlight">Flex item 2</div>
  <div class="p-2 bd-highlight">Flex item 3</div>
</div>
<div class="d-flex flex-row-reverse bd-highlight">
  <div class="p-2 bd-highlight">Flex item 1</div>
  <div class="p-2 bd-highlight">Flex item 2</div>
  <div class="p-2 bd-highlight">Flex item 3</div>
</div>

使用 .flex-column 設置垂直方向,或者使用 .flex-column-reverse 作垂直方向的反轉。

Flex item 1
Flex item 2
Flex item 3
Flex item 1
Flex item 2
Flex item 3
<div class="d-flex flex-column bd-highlight mb-3">
  <div class="p-2 bd-highlight">Flex item 1</div>
  <div class="p-2 bd-highlight">Flex item 2</div>
  <div class="p-2 bd-highlight">Flex item 3</div>
</div>
<div class="d-flex flex-column-reverse bd-highlight">
  <div class="p-2 bd-highlight">Flex item 1</div>
  <div class="p-2 bd-highlight">Flex item 2</div>
  <div class="p-2 bd-highlight">Flex item 3</div>
</div>

flex-direction 的響應式變化。

  • .flex-row
  • .flex-row-reverse
  • .flex-column
  • .flex-column-reverse
  • .flex-sm-row
  • .flex-sm-row-reverse
  • .flex-sm-column
  • .flex-sm-column-reverse
  • .flex-md-row
  • .flex-md-row-reverse
  • .flex-md-column
  • .flex-md-column-reverse
  • .flex-lg-row
  • .flex-lg-row-reverse
  • .flex-lg-column
  • .flex-lg-column-reverse
  • .flex-xl-row
  • .flex-xl-row-reverse
  • .flex-xl-column
  • .flex-xl-column-reverse
  • .flex-xxl-row
  • .flex-xxl-row-reverse
  • .flex-xxl-column
  • .flex-xxl-column-reverse

調整內容

使用 flexbox 容器上的 justify-content 通用類別改變 flex 物件在主軸上的對齊 (x 軸開始,如果 flex-direction: column 則為 y 軸)。從 start (瀏覽器預設),endcenterbetweenaroundevenly 中做選擇。

Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
<div class="d-flex justify-content-start">...</div>
<div class="d-flex justify-content-end">...</div>
<div class="d-flex justify-content-center">...</div>
<div class="d-flex justify-content-between">...</div>
<div class="d-flex justify-content-around">...</div>
<div class="d-flex justify-content-evenly">...</div>

justify-content 的響應式變化。

  • .justify-content-start
  • .justify-content-end
  • .justify-content-center
  • .justify-content-between
  • .justify-content-around
  • .justify-content-evenly
  • .justify-content-sm-start
  • .justify-content-sm-end
  • .justify-content-sm-center
  • .justify-content-sm-between
  • .justify-content-sm-around
  • .justify-content-sm-evenly
  • .justify-content-md-start
  • .justify-content-md-end
  • .justify-content-md-center
  • .justify-content-md-between
  • .justify-content-md-around
  • .justify-content-md-evenly
  • .justify-content-lg-start
  • .justify-content-lg-end
  • .justify-content-lg-center
  • .justify-content-lg-between
  • .justify-content-lg-around
  • .justify-content-lg-evenly
  • .justify-content-xl-start
  • .justify-content-xl-end
  • .justify-content-xl-center
  • .justify-content-xl-between
  • .justify-content-xl-around
  • .justify-content-xl-evenly
  • .justify-content-xxl-start
  • .justify-content-xxl-end
  • .justify-content-xxl-center
  • .justify-content-xxl-between
  • .justify-content-xxl-around
  • .justify-content-xxl-evenly

對齊物件

在 flexbox 容器上使用 align-items 工具改變橫軸上 flex 物件的對齊 (y 軸開始,如果設定 flex-direction: column 則為 x 軸),從 startendcenterbaseline 或是 stretch (瀏覽器預設) 中做選擇。

Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
<div class="d-flex align-items-start">...</div>
<div class="d-flex align-items-end">...</div>
<div class="d-flex align-items-center">...</div>
<div class="d-flex align-items-baseline">...</div>
<div class="d-flex align-items-stretch">...</div>

align-items 包含的響應式變化。

  • .align-items-start
  • .align-items-end
  • .align-items-center
  • .align-items-baseline
  • .align-items-stretch
  • .align-items-sm-start
  • .align-items-sm-end
  • .align-items-sm-center
  • .align-items-sm-baseline
  • .align-items-sm-stretch
  • .align-items-md-start
  • .align-items-md-end
  • .align-items-md-center
  • .align-items-md-baseline
  • .align-items-md-stretch
  • .align-items-lg-start
  • .align-items-lg-end
  • .align-items-lg-center
  • .align-items-lg-baseline
  • .align-items-lg-stretch
  • .align-items-xl-start
  • .align-items-xl-end
  • .align-items-xl-center
  • .align-items-xl-baseline
  • .align-items-xl-stretch
  • .align-items-xxl-start
  • .align-items-xxl-end
  • .align-items-xxl-center
  • .align-items-xxl-baseline
  • .align-items-xxl-stretch

自身對齊

使用 flexbox 物件上的 align-self 通用類別單獨改變在橫軸上的對齊 (y 軸開始,如果設定 flex-direction: column,則為 x 軸)。從與 align-items 相同的選項中選擇: startendcenterbaseline、或是 stretch (溜覽器預設)。

Flex item
Aligned flex item
Flex item
Flex item
Aligned flex item
Flex item
Flex item
Aligned flex item
Flex item
Flex item
Aligned flex item
Flex item
Flex item
Aligned flex item
Flex item
<div class="align-self-start">Aligned flex item</div>
<div class="align-self-end">Aligned flex item</div>
<div class="align-self-center">Aligned flex item</div>
<div class="align-self-baseline">Aligned flex item</div>
<div class="align-self-stretch">Aligned flex item</div>

align-self 的響應式變化。

  • .align-self-start
  • .align-self-end
  • .align-self-center
  • .align-self-baseline
  • .align-self-stretch
  • .align-self-sm-start
  • .align-self-sm-end
  • .align-self-sm-center
  • .align-self-sm-baseline
  • .align-self-sm-stretch
  • .align-self-md-start
  • .align-self-md-end
  • .align-self-md-center
  • .align-self-md-baseline
  • .align-self-md-stretch
  • .align-self-lg-start
  • .align-self-lg-end
  • .align-self-lg-center
  • .align-self-lg-baseline
  • .align-self-lg-stretch
  • .align-self-xl-start
  • .align-self-xl-end
  • .align-self-xl-center
  • .align-self-xl-baseline
  • .align-self-xl-stretch
  • .align-self-xxl-start
  • .align-self-xxl-end
  • .align-self-xxl-center
  • .align-self-xxl-baseline
  • .align-self-xxl-stretch

填滿

在一系列的同級元素上使用 .flex-fill 來強制設定它們的寬度與內容相等(如果它們的內容不超過邊框,則各個寬度相等),同時佔用所有可用的水平空間。

Flex item with a lot of content
Flex item
Flex item
<div class="d-flex bd-highlight">
  <div class="p-2 flex-fill bd-highlight">Flex item with a lot of content</div>
  <div class="p-2 flex-fill bd-highlight">Flex item</div>
  <div class="p-2 flex-fill bd-highlight">Flex item</div>
</div>

flex-fill 同樣包含響應式的變化。

  • .flex-fill
  • .flex-sm-fill
  • .flex-md-fill
  • .flex-lg-fill
  • .flex-xl-fill
  • .flex-xxl-fill

伸縮值

使用 .flex-grow-* 通用類別來切換 flex 項目彈性增長、填充可用空間的能力。在下面的範例中,.flex-grow-1 元素使用它可以使用的所有可用空間,同時允許剩餘的兩個 flex 物件保留必要的空間。

Flex item
Flex item
Third flex item
<div class="d-flex bd-highlight">
  <div class="p-2 flex-grow-1 bd-highlight">Flex item</div>
  <div class="p-2 bd-highlight">Flex item</div>
  <div class="p-2 bd-highlight">Third flex item</div>
</div>

如果需要,使用 .flex-shrink-* 通用類別來切換項目的縮小能力。在下面的範例中,帶有 .flex-shrink-1 的第二個 flex 項目的文字內容會被強制換行,”收縮” 以允許更多空間用於上一個帶有 .w-100 的 flex 項目。

Flex item
Flex item
<div class="d-flex bd-highlight">
  <div class="p-2 w-100 bd-highlight">Flex item</div>
  <div class="p-2 flex-shrink-1 bd-highlight">Flex item</div>
</div>

flex-growflex-shrink 也包含響應式的變化。

  • .flex-{grow|shrink}-0
  • .flex-{grow|shrink}-1
  • .flex-sm-{grow|shrink}-0
  • .flex-sm-{grow|shrink}-1
  • .flex-md-{grow|shrink}-0
  • .flex-md-{grow|shrink}-1
  • .flex-lg-{grow|shrink}-0
  • .flex-lg-{grow|shrink}-1
  • .flex-xl-{grow|shrink}-0
  • .flex-xl-{grow|shrink}-1
  • .flex-xxl-{grow|shrink}-0
  • .flex-xxl-{grow|shrink}-1

自動的 margins

當你混用 Flex 對齊與 auto margin 時候,Flexbox 可以執行一些令人驚艷的功能。下面的範例是透過自動 margin 來控制 flex 項目的三個案例:預設(無自動 margin),向右推兩個項目 (.me-auto),並向左推兩個項目 (.ms-auto)。

Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
<div class="d-flex bd-highlight mb-3">
  <div class="p-2 bd-highlight">Flex item</div>
  <div class="p-2 bd-highlight">Flex item</div>
  <div class="p-2 bd-highlight">Flex item</div>
</div>

<div class="d-flex bd-highlight mb-3">
  <div class="me-auto p-2 bd-highlight">Flex item</div>
  <div class="p-2 bd-highlight">Flex item</div>
  <div class="p-2 bd-highlight">Flex item</div>
</div>

<div class="d-flex bd-highlight mb-3">
  <div class="p-2 bd-highlight">Flex item</div>
  <div class="p-2 bd-highlight">Flex item</div>
  <div class="ms-auto p-2 bd-highlight">Flex item</div>
</div>

搭配 align-items

混合以下屬性 align-itemsflex-direction: column,和 margin-top: automargin-bottom: auto,會將一個 flex 項目移動到容器的頂部或底部。

Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
<div class="d-flex align-items-start flex-column bd-highlight mb-3" style="height: 200px;">
  <div class="mb-auto p-2 bd-highlight">Flex item</div>
  <div class="p-2 bd-highlight">Flex item</div>
  <div class="p-2 bd-highlight">Flex item</div>
</div>

<div class="d-flex align-items-end flex-column bd-highlight mb-3" style="height: 200px;">
  <div class="p-2 bd-highlight">Flex item</div>
  <div class="p-2 bd-highlight">Flex item</div>
  <div class="mt-auto p-2 bd-highlight">Flex item</div>
</div>

Wrap

改變 Flex 項目在 Flex 容器中換行的方式。可以選擇使用 .flex-nowrap 完全不換行 (瀏覽器預設),使用 .flex-wrap 進行換行,或使用 .flex-wrap-reverse 進行反向換行。

Flex item
Flex item
Flex item
Flex item
Flex item
<div class="d-flex flex-nowrap">
  ...
</div>
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
<div class="d-flex flex-wrap">
  ...
</div>
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
<div class="d-flex flex-wrap-reverse">
  ...
</div>

flex-wrap 也包含響應式變化。

  • .flex-nowrap
  • .flex-wrap
  • .flex-wrap-reverse
  • .flex-sm-nowrap
  • .flex-sm-wrap
  • .flex-sm-wrap-reverse
  • .flex-md-nowrap
  • .flex-md-wrap
  • .flex-md-wrap-reverse
  • .flex-lg-nowrap
  • .flex-lg-wrap
  • .flex-lg-wrap-reverse
  • .flex-xl-nowrap
  • .flex-xl-wrap
  • .flex-xl-wrap-reverse
  • .flex-xxl-nowrap
  • .flex-xxl-wrap
  • .flex-xxl-wrap-reverse

排序

使用 order 通用類別改變特定 flex 項目 顯示 的排序。Bootstrap 僅提供選項將一個物件排在第一個或最後一個,以及重置以使用 DOM 排序。由於 order 只能使用從 0 到 5 的整數值,任何額外值則需要自定義的 CSS。

First flex item
Second flex item
Third flex item
<div class="d-flex flex-nowrap bd-highlight">
  <div class="order-3 p-2 bd-highlight">First flex item</div>
  <div class="order-2 p-2 bd-highlight">Second flex item</div>
  <div class="order-1 p-2 bd-highlight">Third flex item</div>
</div>

order 也包含的響應式屬性。

  • .order-0
  • .order-1
  • .order-2
  • .order-3
  • .order-4
  • .order-5
  • .order-sm-0
  • .order-sm-1
  • .order-sm-2
  • .order-sm-3
  • .order-sm-4
  • .order-sm-5
  • .order-md-0
  • .order-md-1
  • .order-md-2
  • .order-md-3
  • .order-md-4
  • .order-md-5
  • .order-lg-0
  • .order-lg-1
  • .order-lg-2
  • .order-lg-3
  • .order-lg-4
  • .order-lg-5
  • .order-xl-0
  • .order-xl-1
  • .order-xl-2
  • .order-xl-3
  • .order-xl-4
  • .order-xl-5
  • .order-xxl-0
  • .order-xxl-1
  • .order-xxl-2
  • .order-xxl-3
  • .order-xxl-4
  • .order-xxl-5

此外還有響應式的 .order-first.order-last 類別,它們分別透過 order: -1order: 6,來更改元素的 order 順序。

  • .order-first
  • .order-last
  • .order-sm-first
  • .order-sm-last
  • .order-md-first
  • .order-md-last
  • .order-lg-first
  • .order-lg-last
  • .order-xl-first
  • .order-xl-last
  • .order-xxl-first
  • .order-xxl-last

對齊內容

使用 flexbox 容器上的 align-content 通用類別將 flex 項目 一起 對齊於橫軸上。從 start (瀏覽器預設)、endcenterbetweenaround,或 stretch 中選擇。以下為了呈現這通用類別的效果,我們強制執行 flex-wrap: wrap 並增加了 Flex 項目的數量。

注意! 此特性對於單行的 Flex 項目沒有作用。

Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
<div class="d-flex align-content-start flex-wrap">
  ...
</div>
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
<div class="d-flex align-content-end flex-wrap">...</div>
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
<div class="d-flex align-content-center flex-wrap">...</div>
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
<div class="d-flex align-content-between flex-wrap">...</div>
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
<div class="d-flex align-content-around flex-wrap">...</div>
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
Flex item
<div class="d-flex align-content-stretch flex-wrap">...</div>

align-content 也包含響應式變化。

  • .align-content-start
  • .align-content-end
  • .align-content-center
  • .align-content-around
  • .align-content-stretch
  • .align-content-sm-start
  • .align-content-sm-end
  • .align-content-sm-center
  • .align-content-sm-around
  • .align-content-sm-stretch
  • .align-content-md-start
  • .align-content-md-end
  • .align-content-md-center
  • .align-content-md-around
  • .align-content-md-stretch
  • .align-content-lg-start
  • .align-content-lg-end
  • .align-content-lg-center
  • .align-content-lg-around
  • .align-content-lg-stretch
  • .align-content-xl-start
  • .align-content-xl-end
  • .align-content-xl-center
  • .align-content-xl-around
  • .align-content-xl-stretch
  • .align-content-xxl-start
  • .align-content-xxl-end
  • .align-content-xxl-center
  • .align-content-xxl-around
  • .align-content-xxl-stretch

Media object

想要從 Bootstrap 4 複製 media object 元件? 使用一些 flex 通用類別立即重新創建它,這些通用類別比以前擁有更多的靈活性與客製化。

PlaceholderImage
This is some content from a media component. You can replace this with any content and adjust it as needed.
<div class="d-flex">
  <div class="flex-shrink-0">
    <img src="..." alt="...">
  </div>
  <div class="flex-grow-1 ms-3">
    This is some content from a media component. You can replace this with any content and adjust it as needed.
  </div>
</div>

假使你想將圖片旁邊的內容垂直置中:

PlaceholderImage
This is some content from a media component. You can replace this with any content and adjust it as needed.
<div class="d-flex align-items-center">
  <div class="flex-shrink-0">
    <img src="..." alt="...">
  </div>
  <div class="flex-grow-1 ms-3">
    This is some content from a media component. You can replace this with any content and adjust it as needed.
  </div>
</div>

Sass

Utilities API

Flexbox 通用類別在 scss/_utilities.scss 中的 utilities API 中宣告。了解如何使用 utilities API。

    "flex": (
      responsive: true,
      property: flex,
      values: (fill: 1 1 auto)
    ),
    "flex-direction": (
      responsive: true,
      property: flex-direction,
      class: flex,
      values: row column row-reverse column-reverse
    ),
    "flex-grow": (
      responsive: true,
      property: flex-grow,
      class: flex,
      values: (
        grow-0: 0,
        grow-1: 1,
      )
    ),
    "flex-shrink": (
      responsive: true,
      property: flex-shrink,
      class: flex,
      values: (
        shrink-0: 0,
        shrink-1: 1,
      )
    ),
    "flex-wrap": (
      responsive: true,
      property: flex-wrap,
      class: flex,
      values: wrap nowrap wrap-reverse
    ),
    "gap": (
      responsive: true,
      property: gap,
      class: gap,
      values: $spacers
    ),
    "justify-content": (
      responsive: true,
      property: justify-content,
      values: (
        start: flex-start,
        end: flex-end,
        center: center,
        between: space-between,
        around: space-around,
        evenly: space-evenly,
      )
    ),
    "align-items": (
      responsive: true,
      property: align-items,
      values: (
        start: flex-start,
        end: flex-end,
        center: center,
        baseline: baseline,
        stretch: stretch,
      )
    ),
    "align-content": (
      responsive: true,
      property: align-content,
      values: (
        start: flex-start,
        end: flex-end,
        center: center,
        between: space-between,
        around: space-around,
        stretch: stretch,
      )
    ),
    "align-self": (
      responsive: true,
      property: align-self,
      values: (
        auto: auto,
        start: flex-start,
        end: flex-end,
        center: center,
        baseline: baseline,
        stretch: stretch,
      )
    ),
    "order": (
      responsive: true,
      property: order,
      values: (
        first: -1,
        0: 0,
        1: 1,
        2: 2,
        3: 3,
        4: 4,
        5: 5,
        last: 6,
      ),
    ),