Layout And Grid System | Components | BootstrapVue

Có thể bạn quan tâm

BootstrapVue provides several convenient functional components tailored for layout, which can simplify your complex page markup compared to traditional Bootstrap v4 markup. Feel free to switch back and forth between traditional Bootstrap v4 markup (i.e. <div>s and classes) and BootstrapVue's convenient functional layout components.

How it works

Bootstrap's grid system uses a series of containers, rows, and columns to layout and align content. It's built with flexbox and is fully responsive. Below is an example and an in-depth look at how the grid comes together.

<b-container class="bv-example-row"> <b-row> <b-col>1 of 3</b-col> <b-col>2 of 3</b-col> <b-col>3 of 3</b-col> </b-row> </b-container>

The above example creates three equal-width columns on small, medium, large, and extra large devices using Bootstrap v4's predefined grid classes. Those columns are centered in the page with the parent .container.

Breaking it down, here's how it works:

Containers provide a means to center and horizontally pad your site's contents. Use <b-container> for a responsive pixel width or <b-container fluid> for width: 100% across all viewport and device sizes.
Rows are wrappers for columns. Each column has horizontal padding (called a gutter) for controlling the space between them. This padding is then counteracted on the rows with negative margins. This way, all the content in your columns is visually aligned down the left side.
In a grid layout, content must be placed within columns and only columns may be immediate children of rows.
Thanks to flexbox, grid columns without a set width will automatically layout with equal widths. For example, four instances of <b-col sm="auto"> will each automatically be 25% wide for small breakpoints.
Column prop cols indicates the number of columns you'd like to use out of the possible 12 per row regardless of breakpoint (starting at breakpoint xs). So, if you want three equal-width columns at any breakpoint, you can use <b-col cols="4">.
Column props sm, md, lg, xl indicate the number of columns you'd like to use out of the possible 12 per row, at the various breakpoints. So, if you want three equal-width columns at breakpoint sm, you can use <b-col sm="4">. the special value auto can be used to take up the remaining available column space in a row.
Column widths are set in percentages, so they're always fluid and sized relative to their parent element.
Columns have horizontal padding to create the gutters between individual columns, however, you can remove the margin from <b-row> and padding from <b-col> by setting the no-gutters prop on <b-row>.
To make the grid responsive, there are five grid breakpoints, one for each responsive breakpoint: all breakpoints (extra small), small, medium, large, and extra large.
Grid breakpoints are based on minimum width media queries, meaning they apply to that one breakpoint and all those above it (e.g., <b-col sm="4"> applies to small, medium, large, and extra large devices, but not the first xs breakpoint).
You can use predefined grid classes or Sass mixins for more semantic markup.

Be aware of the limitations and bugs around flexbox, like the inability to use some HTML elements as flex containers.

Containers <b-container>

Containers (<b-container>) are the most basic layout element in Bootstrap. Choose from a responsive, fixed-width container (meaning its max-width changes at each breakpoint) by default, or fluid-width (meaning it's 100% wide all the time) by setting 'fluid' prop, or responsive containers where the container is fluid up until a specific breakpoint (requires Bootstrap CSS v4.4+).

While containers can be nested, most layouts do not require a nested container.

The default breakpoint widths can be configured using Bootstrap V4.x SCSS variables. See the Theming reference page for additional details, and the table in the Grid options section below.

Default container

The default <b-container> is a responsive, fixed-width container, meaning its max-width changes at each viewport width breakpoint.

<b-container>  </b-container>

Fluid width container

Using the fluid prop on <b-container> will render a container that is always 100% width, regardless of viewport breakpoint.

<b-container fluid>  </b-container>

Setting the fluid prop to true (or an empty string) is equivalent to the Bootstrap .container-fluid class.

Responsive fluid containers

Requires Bootstrap v4.4+ CSS

Responsive containers are new in Bootstrap v4.4. They allow you to specify a container that is 100% wide (fluid) until particular breakpoint is reached at which point a max-width is applied. For example, setting prop fluid to 'md' will render a container that is 100% wide to start until the 'md' breakpoint is reached, at which point it will become a standard non-fluid container.

<b-container fluid="sm"> 100% wide until small breakpoint </b-container> <b-container fluid="md"> 100% wide until medium breakpoint </b-container> <b-container fluid="lg"> 100% wide until large breakpoint </b-container> <b-container fluid="xl"> 100% wide until extra large breakpoint </b-container>

Setting the fluid prop to a breakpoint name translates to the Bootstrap class .container-{breakpoint}.

Refer to the Grid options section table below for the default container width values.

Rows <b-row> and <b-form-row>

Rows are wrappers for columns. Each column has horizontal padding (called a gutter) for controlling the space between them. This padding is then counteracted on the rows with negative margins. This way, all the content in your columns is visually aligned down the left side.

You can remove the margin from <b-row> and padding from <b-col> by setting the no-gutters prop on <b-row>.

Or, for compact margins (smaller gutters between columns), use the <b-form-row> component, which is typically used when laying out forms.

Columns <b-col>

<b-col> Must be placed inside a <b-row> component, or an element (such as a <div>) that has the class row applied to it, or - in the case of forms - inside a <b-form-row> component (to obtain columns with more compact margins).

Grid options

While Bootstrap uses em or rem units for defining most sizes, pxs are used for grid breakpoints and container widths. This is because the viewport width is in pixels and does not change with the font size.

See how aspects of the Bootstrap grid system work across multiple devices with a handy table.

Extra small (xs) <576px	Small (sm) ≥576px	Medium (md) ≥768px	Large (lg) ≥992px	Extra large (xl) ≥1200px
Max container width	None (auto)	540px	720px	960px	1140px
Prop	cols="*"	sm="*"	md="*"	lg="*"	xl="*"
# of columns	12
Gutter width	30px (15px on each side of a column)
Nestable	Yes
Offset	offset="*"	offset-sm="*"	offset-md="*"	offset-lg="*"	offset-xl="*"
Order	order="*"	order-sm="*"	order-md="*"	order-lg="*"	order-xl="*"

Notes:

There is no xs prop. The cols prop refers to the xs (smallest) breakpoint.
The above breakpoint values and names are the Bootstrap defaults. They can be customized via SCSS variables, and (if also using custom breakpoint names), via the BootstrapVue global configuration.

Container sizes

The following table outlines the default container maximum widths at the various breakpoints. These may vary if you are using custom themed Bootstrap v4 SCSS/CSS.

Container type	Extra small <576px	Small ≥576px	Medium ≥768px	Large ≥992px	Extra large ≥1200px
default	100%	540px	720px	960px	1140px
fluid	100%	100%	100%	100%	100%
fluid="sm"	100%	540px	720px	960px	1140px
fluid="md"	100%	100%	720px	960px	1140px
fluid="lg"	100%	100%	100%	960px	1140px
fluid="xl"	100%	100%	100%	100%	1140px

Refer to the Containers <b-container> section section above for additional information

Auto-layout columns

Utilize breakpoint-specific column classes for easy column sizing without an explicit numbered prop like <b-col sm="6">.

Equal-width columns

For example, here are two grid layouts that apply to every device and viewport, from xs to xl. Add any number of unit-less classes for each breakpoint you need and every column will be the same width.

<b-container class="bv-example-row"> <b-row> <b-col>1 of 2</b-col> <b-col>2 of 2</b-col> </b-row> <b-row> <b-col>1 of 3</b-col> <b-col>2 of 3</b-col> <b-col>3 of 3</b-col> </b-row> </b-container>

Equal-width multi-line

Create equal-width columns that span multiple lines by inserting a .w-100 where you want the columns to break to a new line. Make the breaks responsive by mixing .w-100 with some responsive display utilities.

There was a Safari flexbox bug that prevented this from working without an explicit flex-basis or border. There are workarounds for older browser versions, but they shouldn't be necessary if your target browsers don't fall into the buggy versions.

<b-container class="bv-example-row"> <b-row> <b-col>Column</b-col> <b-col>Column</b-col> <div class="w-100"></div> <b-col>Column</b-col> <b-col>Column</b-col> </b-row> </b-container>

Setting one column width

Auto-layout for flexbox grid columns also means you can set the width of one column and have the sibling columns automatically resize around it. You may use predefined grid classes (as shown below), grid mixins, or inline widths. Note that the other columns will resize no matter the width of the center column.

<b-container class="bv-example-row"> <b-row class="text-center"> <b-col>1 of 3</b-col> <b-col cols="8">2 of 3 (wider)</b-col> <b-col>3 of 3</b-col> </b-row> <b-row class="text-center"> <b-col>1 of 3</b-col> <b-col cols="5">2 of 3 (wider)</b-col> <b-col>3 of 3</b-col> </b-row> </b-container>

Variable width content

Use {breakpoint}="auto" props to size columns based on the natural width of their content.

<b-container class="bv-example-row"> <b-row class="justify-content-md-center"> <b-col col lg="2">1 of 3</b-col> <b-col cols="12" md="auto">Variable width content</b-col> <b-col col lg="2">3 of 3</b-col> </b-row> <b-row> <b-col>1 of 3</b-col> <b-col cols="12" md="auto">Variable width content</b-col> <b-col col lg="2">3 of 3</b-col> </b-row> </b-container>

Responsive classes

Bootstrap's grid includes five tiers of predefined classes for building complex responsive layouts. Customize the size of your columns on extra small, small, medium, large, or extra large devices however you see fit.

All breakpoints

For grids that are the same from the smallest of devices to the largest, use the col and cols="*" props. Specify a number of cols when you need a particularly sized column; otherwise, feel free to stick to col (which is applied automatically if no cols are specified).

<b-container class="bv-example-row"> <b-row> <b-col>col</b-col> <b-col>col</b-col> <b-col>col</b-col> <b-col>col</b-col> </b-row> <b-row> <b-col cols="8">col-8</b-col> <b-col cols="4">col-4</b-col> </b-row> </b-container>

Stacked to horizontal

Using a single set of sm="*" or sm (boolean for equal width @sm) props, you can create a basic grid system that starts out stacked on extra small devices before becoming horizontal on desktop (medium) devices.

<b-container class="bv-example-row"> <b-row> <b-col sm="8">col-sm-8</b-col> <b-col sm="4">col-sm-4</b-col> </b-row> <b-row> <b-col sm>col-sm</b-col> <b-col sm>col-sm</b-col> <b-col sm>col-sm</b-col> </b-row> </b-container>

Mix and match

Don't want your columns to simply stack in some grid tiers? Use a combination of different props for each tier as needed. See the example below for a better idea of how it all works.

<b-container class="bv-example-row">  <b-row> <b-col cols="12" md="8">cols="12" md="8"</b-col> <b-col cols="6" md="4">cols="6" md="4"</b-col> </b-row>  <b-row> <b-col cols="6" md="4">cols="6" md="4"</b-col> <b-col cols="6" md="4">cols="6" md="4"</b-col> <b-col cols="6" md="4">cols="6" md="4"</b-col> </b-row>  <b-row> <b-col cols="6">cols="6"</b-col> <b-col cols="6">cols="6"</b-col> </b-row> </b-container>

Alignment

Use flexbox alignment utilities to vertically and horizontally align columns.

Note: Internet Explorer 11 does not support vertical alignment of flex items when the flex container has a min-height as shown below. See Flexbugs #3 for more details.

Vertical alignment

For vertical alignment of all grid cells in a row, use the align-v prop on <b-row>. Possible values are 'start', 'center', 'end', 'baseline', and 'stretch':

<b-container class="bv-example-row bv-example-row-flex-cols"> <b-row align-v="start"> <b-col>One of three columns</b-col> <b-col>One of three columns</b-col> <b-col>One of three columns</b-col> </b-row> <b-row align-v="center"> <b-col>One of three columns</b-col> <b-col>One of three columns</b-col> <b-col>One of three columns</b-col> </b-row> <b-row align-v="end"> <b-col>One of three columns</b-col> <b-col>One of three columns</b-col> <b-col>One of three columns</b-col> </b-row> <b-row align-v="baseline"> <b-col style="font-size: 0.75rem;">One of three columns</b-col> <b-col>One of three columns</b-col> <b-col style="font-size: 1.25rem;">One of three columns</b-col> </b-row> <b-row align-v="stretch"> <b-col>One of three columns</b-col> <b-col>One of three columns</b-col> <b-col>One of three columns</b-col> </b-row> </b-container>

For individual grid cell vertical alignment, use the align-self prop on <b-col>. Possible values are 'start', 'center', 'end', 'baseline', and 'stretch':

<b-container class="bv-example-row bv-example-row-flex-cols"> <b-row> <b-col align-self="start">One of three columns</b-col> <b-col align-self="center">One of three columns</b-col> <b-col align-self="end">One of three columns</b-col> </b-row> <b-row> <b-col align-self="baseline">One of two columns</b-col> <b-col align-self="stretch">One of two columns</b-col> </b-row> </b-container>

Horizontal alignment

To horizontally align grid cells within a row, use the align-h prop on <b-row>. Possible values are: 'start', 'center', 'end', 'around', and 'between':

<b-container class="bv-example-row"> <b-row align-h="start"> <b-col cols="4">One of two columns</b-col> <b-col cols="4">One of two columns</b-col> </b-row> <b-row align-h="center"> <b-col cols="4">One of two columns</b-col> <b-col cols="4">One of two columns</b-col> </b-row> <b-row align-h="end"> <b-col cols="4">One of two columns</b-col> <b-col cols="4">One of two columns</b-col> </b-row> <b-row align-h="around"> <b-col cols="4">One of two columns</b-col> <b-col cols="4">One of two columns</b-col> </b-row> <b-row align-h="between"> <b-col cols="4">One of two columns</b-col> <b-col cols="4">One of two columns</b-col> </b-row> </b-container>

Reordering

Ordering columns

Use order-* props for controlling the visual order of your content. These props are responsive, so you can set the order by breakpoint (e.g., order="1" order-md="2"). Includes support for 1 through 12 across all five grid tiers. <b-col> defaults to an order value of 0.

<b-container fluid class="bv-example-row"> <b-row class="mb-3"> <b-col>First in DOM, no order applied</b-col> <b-col order="5">Second in DOM, with a larger order</b-col> <b-col order="1">Third in DOM, with an order of 1</b-col> </b-row> <b-row class="mb-3"> <b-col order="6">First in DOM, with order of 6</b-col> <b-col order="1">Second in DOM, with an order of 1</b-col> <b-col>Third in DOM, no order applied</b-col> </b-row> </b-container>

Ordering is controlled by flexbox's CSS style order.

Offsetting columns

You can offset grid columns in two ways: our responsive offset-* props or the margin utility classes. Grid offset-* props are sized to match columns while margins utility classes are more useful for quick layouts where the width of the offset is variable.

<b-container fluid class="bv-example-row"> <b-row> <b-col md="4">md="4"</b-col> <b-col md="4" offset-md="4">md="4" offset-md="4"</b-col> </b-row> <b-row> <b-col md="3" offset-md="3">md="3" offset-md="3"</b-col> <b-col md="3" offset-md="3">md="3" offset-md="3"</b-col> </b-row> <b-row> <b-col md="6" offset-md="3">md="6" offset-md="3"</b-col> </b-row> </b-container>

In addition to column clearing at responsive breakpoints, you may need to reset offsets by setting the offset to 0 at a larger breakpoint:

<b-container fluid class="bv-example-row"> <b-row> <b-col sm="5" md="6">sm="5" md="6"</b-col> <b-col sm="5" offset-sm="2" md="6" offset-md="0">sm="5" offset-sm="2" md="6" offset-md="0"</b-col> </b-row> <b-row> <b-col sm="6" md="5" lg="6">sm="6" md="5" lg="6"</b-col> <b-col sm="6" md="5" offset-md="2" lg="6" offset-lg="0">sm="6" md="5" offset-md="2" col-lg="6" offset-lg="0"</b-col> </b-row> </b-container>

Margin utilities on columns

With the move to flexbox in Bootstrap v4, you can use margin and spacing utility classes like .mr-auto to force sibling columns away from one another.

<b-container fluid class="text-light text-center"> <b-row class="mb-3"> <b-col md="4" class="p-3 bg-info">md="4"</b-col> <b-col md="4" class="ml-auto p-3 bg-info">md="4" .ml-auto</b-col> </b-row> <b-row class="mb-3"> <b-col md="3" class="ml-md-auto p-3 bg-info">md="3" .ml-md-auto</b-col> <b-col md="3" class="ml-md-auto p-3 bg-info">md="3" .ml-md-auto</b-col> </b-row> <b-row> <b-col cols="auto" class="mr-auto p-3 bg-info">cols="auto" .mr-auto</b-col> <b-col cols="auto" class="p-3 bg-info">cols="auto"</b-col> </b-row> </b-container>

Nesting grids

To nest your content with the default grid, add a new <b-row> and set of <b-col> components within an existing <b-col> component. Nested rows should include a set of columns that add up to 12 or fewer (it is not required that you use all 12 available columns).

<b-container fluid class="bv-example-row"> <b-row> <b-col sm="9"> Level 1: sm="9" <b-row> <b-col cols="8" sm="6">Level 2: cols="8" sm="6"</b-col> <b-col cols="4" sm="6">Level 2: cols="4" sm="6"</b-col> </b-row> </b-col> </b-row> </b-container>

Row columns

Requires Bootstrap v4.4+ CSS

Use the responsive cols-* props in <b-row> to quickly set the number of columns that best render your content and layout. Whereas normal column widths are apply to the individual <b-col> columns (e.g., <b-col md="4">), the row columns col-* props are set on the parent <b-row> as a shortcut.

Use these row columns to quickly create basic grid layouts or to control your card layouts. The default maximum number of row columns in Bootstrap v4.4 is 6 (unlike the regular columns which have a default maximum of 12 columns)

The value specified in the <b-row> prop(s) is the number of columns to create per row (whereas the props on <b-col> refer to the number of columns to occupy).

<b-container class="bv-example-row mb-3"> <b-row cols="2"> <b-col>Column</b-col> <b-col>Column</b-col> <b-col>Column</b-col> <b-col>Column</b-col> </b-row> </b-container> <b-container class="bv-example-row mb-3"> <b-row cols="3"> <b-col>Column</b-col> <b-col>Column</b-col> <b-col>Column</b-col> <b-col>Column</b-col> </b-row> </b-container> <b-container class="bv-example-row mb-3"> <b-row cols="4"> <b-col>Column</b-col> <b-col>Column</b-col> <b-col>Column</b-col> <b-col>Column</b-col> </b-row> </b-container> <b-container class="bv-example-row"> <b-row cols="4"> <b-col>Column</b-col> <b-col>Column</b-col> <b-col cols="6">Column</b-col> <b-col>Column</b-col> </b-row> </b-container>

You can control the number of columns at each breakpoint level via the following <b-row> props:

cols for xs and up screens
cols-sm for sm and up screens
cols-md for md and up screens
cols-lg for lg and up screens
cols-xl for xl and up screens

<b-container class="bv-example-row"> <b-row cols="1" cols-sm="2" cols-md="4" cols-lg="6"> <b-col>Column</b-col> <b-col>Column</b-col> <b-col>Column</b-col> <b-col>Column</b-col> <b-col>Column</b-col> <b-col>Column</b-col> </b-row> </b-container>

Utilities for layout

For faster mobile-friendly and responsive development, Bootstrap includes dozens of utility classes for showing, hiding, aligning, and spacing content.

Changing display

Use Bootstrap's display utilities for responsively toggling common values of the display property. Mix it with the grid system, content, or components to show or hide them across specific viewports.

Flexbox options

Bootstrap 4 is built with flexbox, but not every element’s display has been changed to display: flex as this would add many unnecessary overrides and unexpectedly change key browser behaviors. Most of the components are built with flexbox enabled.

Should you need to add display: flex to an element, do so with .d-flex or one of the responsive variants (e.g., .d-sm-flex). You’ll need this class or display value to allow the use of the extra flexbox utilities for sizing, alignment, spacing, and more.

Margin and padding

Use the margin and padding spacing utilities to control how elements and components are spaced and sized. Bootstrap 4 includes a five-level scale for spacing utilities, based on a 1rem value default SASS $spacer variable. Choose values for all viewports (e.g., .mr-3 for margin-right: 1rem), or pick responsive variants to target specific viewports (e.g., .mr-md-3 for margin-right: 1rem starting at the md breakpoint).

Toggle visibility

When toggling display isn’t needed, you can toggle the visibility of an element with the visibility utility classes. Invisible elements will still affect the layout of the page, but are visually hidden from visitors.

Từ khóa » Html Col-md-5