弹性 | Flex
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。
启用柔性行为
应用display
实用程序创建一个flexbox容器并将直接的子元素转换为flex项目。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">I'm a flexbox container!</div>
<div class="d-inline-flex p-2">I'm an inline flexbox container!</div>
响应变化也存在.d-flex
和.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
使用方向工具在柔性容器中设置柔性物品的方向。在大多数情况下,您可以省略浏览器默认的水平类row
。但是,您可能会遇到需要明确设置此值的情况(如响应式布局)。
使用.flex-row
设置在水平方向(在浏览器默认值),或者.flex-row-reverse
开始从相对侧上的水平方向上。
<div class="d-flex flex-row">
<div class="p-2">Flex item 1</div>
<div class="p-2">Flex item 2</div>
<div class="p-2">Flex item 3</div>
</div>
<div class="d-flex flex-row-reverse">
<div class="p-2">Flex item 1</div>
<div class="p-2">Flex item 2</div>
<div class="p-2">Flex item 3</div>
</div>
使用.flex-column
设定垂直方向,或者.flex-column-reverse
开始从相对侧上的垂直方向。
<div class="d-flex flex-column">
<div class="p-2">Flex item 1</div>
<div class="p-2">Flex item 2</div>
<div class="p-2">Flex item 3</div>
</div>
<div class="d-flex flex-column-reverse">
<div class="p-2">Flex item 1</div>
<div class="p-2">Flex item 2</div>
<div class="p-2">Flex item 3</div>
</div>
响应变化也存在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
对齐内容
justify-content
在flexbox容器上使用实用程序来更改主轴上的flex项目的对齐方式(x轴开始,y轴为if flex-direction: column
)。选择start
(浏览器的默认),end
,center
,between
或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>
响应变化也存在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
align-items
在flexbox容器上使用实用程序来更改横轴上的flex项目的对齐方式(y轴为开始,x轴为if flex-direction: column
)。选择start
,end
,center
,baseline
,或者stretch
(默认浏览器)。
<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>
响应变化也存在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self
align-self
在Flexbox项目上使用实用程序来单独更改交叉轴上的对齐方式(要开始的是y轴,如果是x轴flex-direction: column
)。选择相同的选项align-items
:start
,end
,center
,baseline
,或者stretch
(默认浏览器)。
<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>
响应变化也存在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
自动边距
将Flex对齐与自动边距混合时,Flexbox可以做一些非常棒的事情。下面显示的是通过自动边距控制弹性项目的三个示例:默认(无自动边距),将两个项目向右推(.mr-auto
),并将两个项目向左推(.ml-auto
)。
不幸的是,IE10和IE11不能正确支持父项具有非默认 justify-content
值的弹性项目上的自动边距。有关更多详细信息,请参阅此StackOverflow answer。
<div class="d-flex">
<div class="p-2">Flex item</div>
<div class="p-2">Flex item</div>
<div class="p-2">Flex item</div>
</div>
<div class="d-flex">
<div class="mr-auto p-2">Flex item</div>
<div class="p-2">Flex item</div>
<div class="p-2">Flex item</div>
</div>
<div class="d-flex">
<div class="p-2">Flex item</div>
<div class="p-2">Flex item</div>
<div class="ml-auto p-2">Flex item</div>
</div>
与对齐项
通过混合align-items
,flex-direction: column
和margin-top: auto
或margin-bottom: auto
,将一个Flex项目垂直移动到容器的顶部或底部。
<div class="d-flex align-items-start flex-column" style="height: 200px;">
<div class="mb-auto p-2">Flex item</div>
<div class="p-2">Flex item</div>
<div class="p-2">Flex item</div>
</div>
<div class="d-flex align-items-end flex-column" style="height: 200px;">
<div class="p-2">Flex item</div>
<div class="p-2">Flex item</div>
<div class="mt-auto p-2">Flex item</div>
</div>
包
更改FLEX项在FLEX容器中的包装方式。从没有包装(浏览器默认)中选择.flex-nowrap
,用.flex-wrap
包装或反向包装.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>
响应变化也存在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
使用少数实用程序更改特定弹性项目的可视顺序order
。我们只提供制作项目的首选或最后选项,以及重置使用DOM订单。正如 order
采用任何整数值(例如5
),为所需的任何附加值添加自定义CSS。
<div class="d-flex flex-nowrap">
<div class="order-3 p-2">First flex item</div>
<div class="order-2 p-2">Second flex item</div>
<div class="order-1 p-2">Third flex item</div>
</div>
响应变化也存在order
。
.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-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-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-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-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
使用align-content
Flexbox容器上的实用工具将交叉轴上的Flex项目对齐在一起。选择start
(浏览器的默认),end
,center
,between
,around
或stretch
。为了演示这些实用程序,我们已经实施flex-wrap: wrap
并增加了弹性项目的数量。
提提%21此属性对单行FLEX项没有影响。
<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>
响应变化也存在align-content
。
.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
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