柔性
使用一整套响应式 flexbox 实用程序快速管理网格列、导航、组件等的布局、对齐和大小。对于更复杂的实现,可能需要自定义 CSS。
启用弹性行为
应用display
实用程序来创建 flexbox 容器并将直接子元素转换为 flex 项。Flex 容器和项目可以通过额外的 flex 属性进一步修改。
<div class="d-flex p-2 bd-highlight">I'm a flexbox container!</div>
<div class="d-inline-flex p-2 bd-highlight">I'm an inline flexbox container!</div>
.d-flex
和也存在响应变体.d-inline-flex
。
.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
方向
使用方向实用程序在 flex 容器中设置 flex 项目的方向。在大多数情况下,您可以在此处省略水平类,因为浏览器默认为row
. 但是,您可能会遇到需要显式设置此值的情况(例如响应式布局)。
用于.flex-row
设置水平方向(浏览器默认),或.flex-row-reverse
从对面开始水平方向。
<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>
用于.flex-column
设置垂直方向,或.flex-column-reverse
从对面开始垂直方向。
<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>
也存在响应变化flex-direction
。
.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
证明内容
使用justify-content
flexbox 容器上的实用程序来更改 flex 项目在主轴上的对齐方式(x 轴开始,y 轴 if flex-direction: column
)。从start
(浏览器默认)、end
、center
、between
或中选择around
。
<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>
也存在响应变化justify-content
。
.justify-content-start
.justify-content-end
.justify-content-center
.justify-content-between
.justify-content-around
.justify-content-sm-start
.justify-content-sm-end
.justify-content-sm-center
.justify-content-sm-between
.justify-content-sm-around
.justify-content-md-start
.justify-content-md-end
.justify-content-md-center
.justify-content-md-between
.justify-content-md-around
.justify-content-lg-start
.justify-content-lg-end
.justify-content-lg-center
.justify-content-lg-between
.justify-content-lg-around
.justify-content-xl-start
.justify-content-xl-end
.justify-content-xl-center
.justify-content-xl-between
.justify-content-xl-around
对齐项目
使用align-items
flexbox 容器上的实用程序来更改 flex 项目在交叉轴上的对齐方式(y 轴开始,x 轴 if flex-direction: column
)。从start
、end
、center
、baseline
或stretch
(浏览器默认)中选择。
<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>
也存在响应变化align-items
。
.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
对齐自我
在 flexbox 项目上使用align-self
实用程序来单独更改它们在交叉轴上的对齐方式(y 轴开始,x 轴 if flex-direction: column
)。align-items
从与: start
、end
、center
、baseline
或stretch
(浏览器默认)相同的选项中进行选择。
<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>
也存在响应变化align-self
。
.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
充满
在一系列同级元素上使用.flex-fill
类来强制它们的宽度等于它们的内容(或者如果它们的内容不超过它们的边界框,则它们的宽度相等),同时占用所有可用的水平空间。
<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>
也存在响应变化flex-fill
。
.flex-fill
.flex-sm-fill
.flex-md-fill
.flex-lg-fill
.flex-xl-fill
增长和收缩
使用.flex-grow-*
实用程序来切换弹性项目的增长能力以填充可用空间。在下面的例子中,.flex-grow-1
元素使用了它可以使用的所有可用空间,同时为剩余的两个弹性项目留出了必要的空间。
<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>
如有必要,使用.flex-shrink-*
实用程序来切换弹性项目的收缩能力。在下面的示例中,第二个带有 的弹性项目.flex-shrink-1
被强制将其内容换行,“收缩”以便为前一个带有 的弹性项目留出更多空间.w-100
。
<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-grow
和也存在响应变体flex-shrink
。
.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
自动边距
当您将 flex 对齐与自动边距混合使用时,Flexbox 可以做一些非常棒的事情。下面显示了三个通过自动边距控制弹性项目的示例:默认(无自动边距)、向右推两个项目(.mr-auto
)和向左推两个项目(.ml-auto
)。
不幸的是,IE10 和 IE11 不能正确支持其父项具有非默认justify-content
值的弹性项目的自动边距。 有关更多详细信息,请参阅此 StackOverflow 答案。
<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="mr-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="ml-auto p-2 bd-highlight">Flex item</div>
</div>
使用对齐项
align-items
通过混合、flex-direction: column
和margin-top: auto
或将一个弹性项目垂直移动到容器的顶部或底部margin-bottom: auto
。
<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>
裹
更改弹性项目在弹性容器中的包装方式。选择完全不换行(浏览器默认设置).flex-nowrap
,用 换行,用 换行.flex-wrap
或反向换行.flex-wrap-reverse
。
<div class="d-flex flex-nowrap">
...
</div>
<div class="d-flex flex-wrap">
...
</div>
<div class="d-flex flex-wrap-reverse">
...
</div>
也存在响应变化flex-wrap
。
.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
命令
使用一些实用程序更改特定弹性项目的视觉顺序。order
我们只提供最先或最后制作项目的选项,以及重置以使用 DOM 顺序。由于order
需要任何整数值(例如5
),为所需的任何附加值添加自定义 CSS。
<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>
也存在响应变化order
。
.order-0
.order-1
.order-2
.order-3
.order-4
.order-5
.order-6
.order-7
.order-8
.order-9
.order-10
.order-11
.order-12
.order-sm-0
.order-sm-1
.order-sm-2
.order-sm-3
.order-sm-4
.order-sm-5
.order-sm-6
.order-sm-7
.order-sm-8
.order-sm-9
.order-sm-10
.order-sm-11
.order-sm-12
.order-md-0
.order-md-1
.order-md-2
.order-md-3
.order-md-4
.order-md-5
.order-md-6
.order-md-7
.order-md-8
.order-md-9
.order-md-10
.order-md-11
.order-md-12
.order-lg-0
.order-lg-1
.order-lg-2
.order-lg-3
.order-lg-4
.order-lg-5
.order-lg-6
.order-lg-7
.order-lg-8
.order-lg-9
.order-lg-10
.order-lg-11
.order-lg-12
.order-xl-0
.order-xl-1
.order-xl-2
.order-xl-3
.order-xl-4
.order-xl-5
.order-xl-6
.order-xl-7
.order-xl-8
.order-xl-9
.order-xl-10
.order-xl-11
.order-xl-12
对齐内容
align-content
在 flexbox 容器上使用实用程序将flex 项在交叉轴上对齐。从start
(浏览器默认)、end
、center
、between
、around
或中选择stretch
。为了演示这些实用程序,我们强制执行flex-wrap: wrap
并增加了弹性项目的数量。
小心!此属性对单行弹性项目没有影响。
<div class="d-flex align-content-start flex-wrap">
...
</div>
<div class="d-flex align-content-end flex-wrap">...</div>
<div class="d-flex align-content-center flex-wrap">...</div>
<div class="d-flex align-content-between flex-wrap">...</div>
<div class="d-flex align-content-around flex-wrap">...</div>
<div class="d-flex align-content-stretch flex-wrap">...</div>
也存在响应变化align-content
。
.align-content-start
.align-content-end
.align-content-center
.align-content-between
.align-content-around
.align-content-stretch
.align-content-sm-start
.align-content-sm-end
.align-content-sm-center
.align-content-sm-between
.align-content-sm-around
.align-content-sm-stretch
.align-content-md-start
.align-content-md-end
.align-content-md-center
.align-content-md-between
.align-content-md-around
.align-content-md-stretch
.align-content-lg-start
.align-content-lg-end
.align-content-lg-center
.align-content-lg-between
.align-content-lg-around
.align-content-lg-stretch
.align-content-xl-start
.align-content-xl-end
.align-content-xl-center
.align-content-xl-between
.align-content-xl-around
.align-content-xl-stretch