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.
This 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
.containerfor a responsive pixel width or
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
paddingis 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
widthwill automatically layout as equal width columns. For example, four instances of
.col-smwill each automatically be 25% wide from the small breakpoint and up. See the auto-layout columns section for more examples.
- 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
widths are set in percentages, so they’re always fluid and sized relative to their parent element.
- Columns have horizontal
paddingto create the gutters between individual columns, however, you can remove the
marginfrom rows and
paddingfrom columns with
- 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.,
.col-sm-4applies to small, medium, large, and extra large devices, but not the first
- You can use predefined grid classes (like
See how aspects of the grid system work across multiple devices:
|Max container width||None (auto)||90%||90%||90%||1250px||1650px|
|# of columns||12|
|Gutter width||30px (15px on each side of a column)|
<div class="container"> <div class="row"> <div class="col-sm"> One of three columns </div> <div class="col-sm"> One of three columns </div> <div class="col-sm"> One of three columns </div> </div> </div> <div class="container"> <div class="row"> <div class="col-sm-8"> col-sm-8 </div> <div class="col-sm-4"> col-sm-4 </div> </div> </div>