CSS Flexible Box Layout

CSS Flexible Box Layout is a module of CSS that defines a CSS box model optimized for user interface design, and the layout of items in one dimension. In the flex layout model, the children of a flex container can be laid out in any direction, and can “flex” their sizes, either growing to fill unused space or shrinking to avoid overflowing the parent. Both horizontal and vertical alignment of the children can be easily manipulated.

Basic Example

In the following example a container has been set to display: flex, which means that the three child items become flex items. The value of justify-content has been set to space-between in order to space the items out evenly on the main axis. An equal amount of space is placed between each item with the left and right items being flush with the edges of the flex container. You can also see that the items are stretching on the cross axis, due to the default value of align-items being stretch. The items stretch to the height of the flex container, making them each appear as tall as the tallest item.


CSS Properties

Alignment Properties

The properties align-content, align-self, align-items and justify-content initially appeared in the Flexbox specification, but are now defined in Box Alignment. The Flexbox spec now refers to the Box Alignment specification for up to date definitions. Also additional alignment properties are now defined in Box Alignment.

Glossary entries


Basic Concepts of Flexbox

An overview of the features of Flexbox

Relationship of Flexbox to other layout methods

How Flexbox relates to other layout methods, and other CSS specifications

Aligning items in a flex container

How the Box Alignment properties work with Flexbox.

Ordering flex items

Explaining the different ways to change the order and direction of items, and covering the potential issues in doing so.

Controlling Ratios of flex items along the main axis

Explaining the flex-grow, flex-shrink and flex-basis properties.

Mastering wrapping of flex items

How to create flex containers with multiple lines and control the display of the items in those lines.

Typical use cases of Flexbox

Common design patterns that are typical Flexbox use cases.

Backwards compatibility of Flexbox

Browser status of Flexbox, interoperability issues and supporting older browsers and versions of the spec


Specification Status Comment
CSS Flexible Box Layout Module Candidate Recommendation Initial definition.

See also


a community-curated list of Flexbox browser bugs and workarounds