The align-content property is a sub-property of the Flexible Box Layout module.

It helps to align a flex container’s lines within it when there is extra space in the cross-axis, similar to how justify-content aligns individual items within the main-axis.

Note, this property has no effect when the flexbox has only a single line.

The align-content property accepts 6 different values:

• flex-start: lines packed to the start of the container
• flex-end: lines packed to the end of the container
• center: lines packed to the center of the container
• space-between: lines evenly distributed; the first line is at the start of the container while the last one is at the end
• space-around: lines evenly distributed with equal space between them
• stretch (default): lines stretch to take up the remaining space

The following figure helps understand how the lines are stacked up in a flex container depending on the align-content value:

Syntax

align-content: flex-start | flex-end | center | space-between | space-around | stretch

.flex-container {
  align-content: space-around;
}

Demo

The following demo shows how lines are stacked out depending on the `align-content` value:

• The red list is set to flex-start
• The yellow list is set to flex-end
• The blue list is set to center
• The green list is set to space-between
• The pink list is set to space-around
• The brown list is set to stretch

Check out this Pen!

Related Properties

• display (flex)
• justify-content
• flex-direction
• flex-flow
• flex-wrap
• align-items

Other Resources

• align-items in the spec
• align-items at MDN
• Advanced cross-browser flexbox
• A guide to Flexbox
• Using Flexbox
• Old Flexbox and new Flexbox

Browser Support

• (modern) means the recent syntax from the specification (e.g. display: flex;)
• (hybrid) means an odd unofficial syntax from 2011 (e.g. display: flexbox;)
• (old) means the old syntax from 2009 (e.g. display: box;)

Chrome	Safari	Firefox	Opera	IE	Android	iOS
21+ (modern) 20- (old)	3.1+ (old)	2-21 (old) 22+ (new)	12.1+ (modern)	10+ (hybrid)	2.1+ (old)	3.2+ (old)

Blackberry browser 10+ supports the new syntax.

For more informations about how to mix syntaxes in order to get the best browser support, please refer to this article (CSS-Tricks) or this article (DevOpera).