User:TheDJ/bootstrap

 =Bootstrap grid demo page= Use our powerful mobile-first flexbox grid to build layouts of all shapes and sizes thanks to a twelve column system, five default responsive tiers, Sass variables and mixins, and dozens of predefined classes.

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.

New to or unfamiliar with flexbox? Read this CSS Tricks flexbox guide for background, terminology, guidelines, and code snippets.

One of three columns One of three columns One of three columns

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

Breaking it down, here’s how it works:

 Containers provide a means to center and horizontally pad your site’s contents. Use  for a responsive pixel width or   for   across all viewport and device sizes. Rows are wrappers for columns. Each column has horizontal  (called a gutter) for controlling the space between them. This  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 specified  will automatically layout as equal width columns. For example, four instances of  will each automatically be 25% wide from the small breakpoint and up. See the auto-layout columns</a> section for more examples.</li> Column classes indicate the number of columns you’d like to use out of the possible 12 per row. So, if you want three equal-width columns across, you can use .</li> Column s are set in percentages, so they’re always fluid and sized relative to their parent element.</li> Columns have horizontal  to create the gutters between individual columns, however, you can remove the   from rows and   from columns with   on the  .</li> To make the grid responsive, there are five grid breakpoints, one for each <a href="/docs/4.0/layout/overview/#responsive-breakpoints">responsive breakpoint</a>: all breakpoints (extra small), small, medium, large, and extra large.</li> Grid breakpoints are based on minimum width media queries, meaning they apply to that one breakpoint and all those above it (e.g.,  applies to small, medium, large, and extra large devices, but not the first   breakpoint).</li> You can use predefined grid classes (like ) or <a href="#sass-mixins">Sass mixins</a> for more semantic markup.</li> </ul>

Be aware of the limitations and <a href="https://github.com/philipwalton/flexbugs">bugs around flexbox</a>, like the <a href="https://github.com/philipwalton/flexbugs#9-some-html-elements-cant-be-flex-containers">inability to use some HTML elements as flex containers</a>.

Grid options
While Bootstrap uses s or  s for defining most sizes,  s are used for grid breakpoints and container widths. This is because the viewport width is in pixels and does not change with the <a href="https://drafts.csswg.org/mediaqueries-3/#units">font size</a>.

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

<th class="text-nowrap" scope="row"># of columns 12 <th class="text-nowrap" scope="row">Gutter width 30px (15px on each side of a column) <th class="text-nowrap" scope="row">Nestable Yes <th class="text-nowrap" scope="row">Column ordering Yes

Auto-layout columns
Utilize breakpoint-specific column classes for easy column sizing without an explicit numbered class like.

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

1 of 2 2 of 2 1 of 3 2 of 3 3 of 3

Equal-width columns can be broken into multiple lines, but there was a <a href="https://github.com/philipwalton/flexbugs#11-min-and-max-size-declarations-are-ignored-when-wrapping-flex-items">Safari flexbox bug</a> that prevented this from working without an explicit  or. There are workarounds for older browser versions, but they shouldn’t be necessary if you’re up-to-date.

Column Column Column Column

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.

1 of 3 2 of 3 (wider) 3 of 3 1 of 3 2 of 3 (wider) 3 of 3

Variable width content
Use  classes to size columns based on the natural width of their content.

1 of 3 Variable width content 3 of 3 1 of 3 Variable width content 3 of 3

Equal-width multi-row
Create equal-width columns that span multiple rows by inserting a  where you want the columns to break to a new line. Make the breaks responsive by mixing the  with some <a href="/docs/4.0/utilities/display/">responsive display utilities</a>.

col col col col

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  and   classes. Specify a numbered class when you need a particularly sized column; otherwise, feel free to stick to.

col col col col col-8 col-4

Stacked to horizontal
Using a single set of  classes, you can create a basic grid system that starts out stacked before becoming horizontal with at the small breakpoint.

col-sm-8 col-sm-4 col-sm col-sm col-sm

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

.col-12 .col-md-8 .col-6 .col-md-4

.col-6 .col-md-4 .col-6 .col-md-4 .col-6 .col-md-4

.col-6 .col-6

Alignment
Use flexbox alignment utilities to vertically and horizontally align columns.

Vertical alignment
One of three columns One of three columns One of three columns One of three columns One of three columns One of three columns One of three columns One of three columns One of three columns

One of three columns One of three columns One of three columns

Horizontal alignment
One of two columns One of two columns One of two columns One of two columns One of two columns One of two columns One of two columns One of two columns One of two columns One of two columns

No gutters
The gutters between columns in our predefined grid classes can be removed with. This removes the negative s from   and the horizontal   from all immediate children columns.

Here’s the source code for creating these styles. Note that column overrides are scoped to only the first children columns and are targeted via <a href="https://developer.mozilla.org/en-US/docs/Web/CSS/Attribute_selectors">attribute selector</a>. While this generates a more specific selector, column padding can still be further customized with <a href="/docs/4.0/utilities/spacing/">spacing utilities</a>.

Need an edge-to-edge design? Drop the parent  or.

In practice, here’s how it looks. Note you can continue to use this with all other predefined grid classes (including column widths, responsive tiers, reorders, and more).

.col-12 .col-sm-6 .col-md-8 .col-6 .col-md-4

Column wrapping
If more than 12 columns are placed within a single row, each group of extra columns will, as one unit, wrap onto a new line.

.col-9 .col-4 Since 9 + 4 = 13 &gt; 12, this 4-column-wide div gets wrapped onto a new line as one contiguous unit. .col-6 Subsequent columns continue along the new line.

Column breaks
Breaking columns to a new line in flexbox requires a small hack: add an element with  wherever you want to wrap your columns to a new line. Normally this is accomplished with multiple s, but not every implementation method can account for this.

.col-6 .col-sm-3 .col-6 .col-sm-3

.col-6 .col-sm-3 .col-6 .col-sm-3

You may also apply this break at specific breakpoints with our <a href="/docs/4.0/utilities/display/">responsive display utilities</a>.

.col-6 .col-sm-4 .col-6 .col-sm-4

.col-6 .col-sm-4 .col-6 .col-sm-4

Order classes
Use  classes for controlling the visual order of your content. These classes are responsive, so you can set the  by breakpoint (e.g.,  ). Includes support for  through   across all five grid tiers.

First, but unordered Second, but last Third, but first

There are also responsive  and   classes that change the   of an element by applying   and  , respectively. These classes can also be intermixed with the numbered  classes as needed.

First, but last Second, but unordered Third, but first

Offsetting columns
You can offset grid columns in two ways: our responsive  grid classes and our <a href="/docs/4.0/utilities/spacing/">margin utilities</a>. Grid classes are sized to match columns while margins are more useful for quick layouts where the width of the offset is variable.

Offset classes
Move columns to the right using  classes. These classes increase the left margin of a column by  columns. For example,  moves   over four columns.

.col-md-4 .col-md-4 .offset-md-4 .col-md-3 .offset-md-3 .col-md-3 .offset-md-3 .col-md-6 .offset-md-3

In addition to column clearing at responsive breakpoints, you may need to reset offsets. See this in action in <a href="/docs/4.0/examples/grid/">the grid example</a>.

.col-sm-5 .col-md-6 .col-sm-5 .offset-sm-2 .col-md-6 .offset-md-0

.col-sm-6 .col-md-5 .col-lg-6 .col-sm-6 .col-md-5 .offset-md-2 .col-lg-6 .offset-lg-0

Margin utilities
With the move to flexbox in v4, you can use margin utilities like  to force sibling columns away from one another.

.col-md-4 .col-md-4 .ml-auto .col-md-3 .ml-md-auto .col-md-3 .ml-md-auto .col-auto .mr-auto .col-auto

Nesting
To nest your content with the default grid, add a new  and set of   columns within an existing   column. 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).

Level 1: .col-sm-9 Level 2: .col-8 .col-sm-6 Level 2: .col-4 .col-sm-6

Sass mixins
NOTE: Not available in this version

When using Bootstrap’s source Sass files, you have the option of using Sass variables and mixins to create custom, semantic, and responsive page layouts. Our predefined grid classes use these same variables and mixins to provide a whole suite of ready-to-use classes for fast responsive layouts.

Variables
NOTE: Not available in this version Variables and maps determine the number of columns, the gutter width, and the media query point at which to begin floating columns. We use these to generate the predefined grid classes documented above, as well as for the custom mixins listed below.

Mixins
NOTE: Not available in this version

Mixins are used in conjunction with the grid variables to generate semantic CSS for individual grid columns.

Example usage
You can modify the variables to your own custom values, or just use the mixins with their default values. Here’s an example of using the default settings to create a two-column layout with a gap between.

Main content Secondary content

Customizing the grid
Using our built-in grid Sass variables and maps, it’s possible to completely customize the predefined grid classes. Change the number of tiers, the media query dimensions, and the container widths—then recompile.

Columns and gutters
The number of grid columns can be modified via Sass variables. is used to generate the widths (in percent) of each individual column while  allows breakpoint-specific widths that are divided evenly across   and   for the column gutters.

Grid tiers
Moving beyond the columns themselves, you may also customize the number of grid tiers. If you wanted just four grid tiers, you’d update the  and   to something like this:

When making any changes to the Sass variables or maps, you’ll need to save your changes and recompile. Doing so will output a brand new set of predefined grid classes for column widths, offsets, and ordering. Responsive visibility utilities will also be updated to use the custom breakpoints. Make sure to set grid values in  (not ,  , or  ).