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One free scan finds every outdated or missing driver and matches the right update for your exact hardware.Free scan · exact hardware matchCSS justify-content aligns or distributes content along a layout-specific axis: the main axis in Flexbox and the inline axis in Grid and multicol. It only has visible work to do when the layout leaves room to align or distribute; it does not affect an ordinary block container.
What does justify-content do?
justify-content controls how a layout container positions or distributes its content within the container’s content box. Its meaning depends on the layout mode. In Flexbox, it distributes available free space among items on a flex line. In Grid, it aligns the grid columns together within the grid container; it does not position one grid item inside its own cell. Multicol containers also use the property along the inline axis. See the MDN reference and the CSS Box Alignment Module Level 3 Working Draft.
The W3C draft describes the role of the property this way: “The content-distribution properties justify-content and align-content control alignment of the box’s content within its content box.” The draft is dated 30 January 2026 and is a Working Draft, not a final Recommendation.
Which axis does it affect?
Flexbox: the main axis
The main axis is set by flex-direction. With the default row, it runs along the flex container’s inline direction; with column, it runs vertically. So justify-content is not inherently a horizontal-centering property: its direction follows the flex layout.
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Grid and multicol: the inline axis
In Grid, the property aligns the columns as a group along the inline axis. In multicol, it acts on the content along that same axis. If grid tracks already fill the available inline space, there may be no remaining room for a different distribution to show.
What do the common values do?
| Value | Effect | Useful when |
|---|---|---|
start / end |
Packs the content toward the logical start or end edge. | You want alignment that follows the layout’s writing direction. |
center |
Centers the content group in the alignment container. | You want the group centered and have considered what happens if it overflows. |
space-between |
Creates equal gaps between items, with no added gap at either outer edge. | You want items such as navigation links to span the available space. |
space-around |
Creates equal gaps between items and half-sized gaps at the edges. | You want looser spacing with smaller outer gaps. |
space-evenly |
Creates equal gaps between items and at both edges. | You want the outer and inner spacing to match. |
stretch |
Behavior depends on layout: it acts like flex-start in Flexbox; in Grid, auto-sized tracks can stretch. |
You are aligning Grid tracks and have checked their sizing behavior. |
These distribution values need room to operate. The same keyword can have different practical effects in different layout modes, so check the container’s layout and sizing rather than assuming a value will create visible gaps.
How do you center items with Flexbox?
For a single flex line, set the container to Flexbox and use justify-content: center. This centers the items along the main axis. To center along the other axis, use the cross-axis alignment property, align-items.
.container {
display: flex;
justify-content: center;
align-items: center;
}Here, justify-content centers along the main axis and align-items aligns the items along the cross axis. If you change flex-direction, the main axis changes too.
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Why is justify-content: center not working?
- Check the layout mode. The element must be a flex, grid, or multicol container. The property has no effect on an ordinary block container.
- Identify the relevant axis. In Flexbox it is the main axis, determined by
flex-direction; in Grid and multicol it is the inline axis. - Look for remaining space. In Flexbox, item sizing happens before distribution. If
flex-growhas consumed the available free space, there is nothing left forjustify-contentto distribute. - Check auto margins. Flex auto margins are resolved before
justify-content; they may absorb the space you expected the property to distribute. - In Grid, inspect the tracks. If the columns already occupy the available inline size, changing the group alignment may not visibly move them.
- Confirm what you intend to align. The property distributes or aligns content as a group. To position an individual item within its area, use an item-alignment property instead.
How is justify-content different from align-items?
In Flexbox, justify-content controls alignment along the main axis, while align-items controls item alignment along the cross axis. For the default row direction, that usually means justify-content affects horizontal distribution and align-items affects vertical alignment, subject to writing direction. In Grid, justify-content aligns the columns as a group; it is not the property for placing an individual grid item inside its grid area.
What other values and compatibility caveats matter?
MDN documents positional values including flex-start, flex-end, left, right, and normal, as well as distribution values and global CSS values. The W3C syntax also allows overflow-position keywords such as safe and unsafe before positional values. Safe alignment is specified to fall back toward the start when the requested alignment would cause overflow; unsafe alignment honors the requested position even when some content may become inaccessible.
Those overflow-position features and related scroll-safety behavior are marked at risk in the 30 January 2026 W3C Working Draft, so verify browser support before relying on them. MDN describes justify-content as widely available and reports availability across browsers since September 2015; that date is MDN’s compatibility summary, not a separate measurement.
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