Bootstrap includes a powerful mobile-first grid system for building layouts of all shapes and sizes based on a 12 column layout. There are multiple tiers, one for each [media query range]({{ site.baseurl }}/layout/media-queries/), made available via our predefined classes or semantic mixins.
Here's how the grid system works:
- There are three major components—containers, rows, and columns.
- Containers—`.container` for fixed width or `.container-fluid` for full width—center your site's contents.
- Rows are horizontal groups of columns that clear floats (when not in [flexbox mode]({{ site.baseurl }}/getting-started/flexbox/)).
- Content should be placed within columns, and only columns may be immediate children of rows.
- You can use predefined grid classes or Sass mixins for more semantic markup.
Bootstrap includes a powerful mobile-first grid system for building layouts of all shapes and sizes. It's based on a 12 column layout and has multiple tiers, one for each [media query range]({{ site.baseurl }}/layout/overview/#responsive-breakpoints). You can use it with Sass mixins or our predefined classes.
## Contents
* Will be replaced with the ToC, excluding the "Contents" header
{:toc}
## Quick start
## How it works
At a high level, here's how the grid system works:
- There are three major components—containers, rows, and columns.
- Containers—`.container` for fixed width or `.container-fluid` for full width—center your site's contents and help align your grid content.
- Rows are horizontal groups of columns that ensure your columns are lined up properly.
- Content should be placed within columns, and only columns may be immediate children of rows.
- 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, you'd use `.col-sm-4`.
- Column `width`s 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.
- There are five grid tiers, one for each [responsive breakpoint]({{ site.baseurl }}/layout/overview/#responsive-breakpoints): extra small, small, medium, large, and extra large.
- Grid tiers are based on minimum widths, meaning they apply to that one tier and all those above it (e.g., `.col-sm-4` applies to small, medium, large, and extra large devices).
- You can use predefined grid classes or Sass mixins for more semantic markup.
- Example grid class
- Example mixins
Sounds good? Great, let's move on to seeing all that in an example.
## Introduction
## Quick start example
Grid systems are used for creating page layouts through a series of rows and columns that house your content. Here's how the Bootstrap grid system works:
If you're using Bootstrap's compiled CSS, this the example you'll want to start with.
- Rows must be placed within a `.container` (fixed-width) or `.container-fluid` (full-width) for proper alignment and padding.
- Use rows to create horizontal groups of columns.
- Content should be placed within columns, and only columns may be immediate children of rows.
- Predefined grid classes like `.row` and `.col-xs-4` are available for quickly making grid layouts. Sass mixins can also be used for more semantic layouts.
- Columns create gutters (gaps between column content) via `padding`. That padding is offset in rows for the first and last column via negative margin on `.row`s.
- The negative margin is why the examples below are outdented. It's so that content within grid columns is lined up with non-grid content.
- Grid columns are created by specifying the number of twelve available columns you wish to span. For example, three equal columns would use three `.col-xs-4`.
- 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.
- Grid classes apply to devices with screen widths greater than or equal to the breakpoint sizes, and override grid classes targeted at smaller devices. Therefore, applying any `.col-md-` class to an element will not only affect its styling on medium devices but also on large devices if a `.col-lg-` class is not present.
{% example html %}
<divclass="container">
<divclass="row">
<divclass="col-sm-4">
One of three columns
</div>
<divclass="col-sm-4">
One of three columns
</div>
<divclass="col-sm-4">
One of three columns
</div>
</div>
</div>
{% endexample %}
Look to the examples for applying these principles to your code.
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 `.container`.
## Grid options
...
...
@@ -50,24 +60,24 @@ See how aspects of the Bootstrap grid system work across multiple devices with a
<tr>
<th></th>
<th>
Extra small devices
<small>Portrait phones (<34em)</small>
Extra small
<small><34em</small>
</th>
<th>
Small devices
<small>Landscape phones (≥34em)</small>
Small
<small>≥34em</small>
</th>
<th>
Medium devices
<small>Tablets (≥48em)</small>
Medium
<small>≥48em</small>
</th>
<th>
Large devices
<small>Desktops (≥62em)</small>
Large
<small>≥62em</small>
</th>
<th>
Extra large devices
<small>Desktops (≥75em)</small>
Extra large
<small>≥75em</small>
</th>
</tr>
</thead>
...
...
@@ -266,18 +276,6 @@ Using a single set of `.col-md-*` grid classes, you can create a basic grid syst
{% endexample %}
</div>
### Example: Fluid container
Turn any fixed-width grid layout into a full-width layout by changing your outermost `.container` to `.container-fluid`.
{% highlight html %}
<divclass="container-fluid">
<divclass="row">
...
</div>
</div>
{% endhighlight %}
### Example: Mobile and desktop
Don't want your columns to simply stack in smaller devices? Use the extra small and medium device grid classes by adding `.col-xs-*` and `.col-md-*` to your columns. See the example below for a better idea of how it all works.
