A Guide To Flexbox CSS Tricks
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A Complete Guide to Flexbox | CSS-Tricks
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A Complete Guide to Flexbox
BY CHRIS COYIER LAST UPDATED ON NOVEMBER 12, 2017
FLEXBOX, LAYOUT
▶ Background
▶ Basics & Terminology
items
container
Properties for the Parent
Properties for the Children
(flex container)
(flex items)
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# display
# order
This defines a flex container; inline or block depending on the
given value. It enables a flex context for all its direct children.
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1
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2
3
CSS
-1
1
2
5
.container {
display: flex; /* or inline-flex */
2
}
2
99
Note that CSS columns have no effect on a flex container.
# flex-direction
By default, flex items are laid out in the source order. However,
the order property controls the order in which they appear
in the flex container.
CSS
.item {
This establishes the main-axis, thus defining the direction flex
items are placed in the flex container. Flexbox is (aside from
order: ; /* default is 0 */
}
optional wrapping) a single-direction layout concept. Think of
flex items as primarily laying out either in horizontal rows or
vertical columns.
# flex-grow
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CSS
1
1
1
.container {
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flex-direction: row | row-reverse | col
2
1
}
This defines the ability for a flex item to grow if necessary. It
row (default): left to right in ltr ; right to left in rtl
row-reverse : right to left in ltr ; left to right in rtl
column : same as row but top to bottom
column-reverse : same as row-reverse but bottom
to top
accepts a unitless value that serves as a proportion. It dictates
what amount of the available space inside the flex container
the item should take up.
If all items have flex-grow set to 1, the remaining space in
the container will be distributed equally to all children. If one of
the children has a value of 2, the remaining space would take
up twice as much space as the others (or it will try to, at least).
CSS
# flex-wrap
.item {
flex-grow: ; /* default 0 */
}
Negative numbers are invalid.
By default, flex items will all try to fit onto one line. You can
change that and allow the items to wrap as needed with this
property.
# flex-shrink
This defines the ability for a flex item to shrink if necessary.
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CSS
CSS
.container{
.item {
flex-wrap: nowrap | wrap | wrap-reverse
}
flex-shrink: ; /* default 1 */
}
nowrap (default): all flex items will be on one line
Negative numbers are invalid.
wrap : flex items will wrap onto multiple lines, from top
to bottom.
wrap-reverse : flex items will wrap onto multiple lines
from bottom to top.
There are some visual demos of flex-wrap here.
# flex-basis
This defines the default size of an element before the
remaining space is distributed. It can be a length (e.g. 20%,
5rem, etc.) or a keyword. The auto keyword means "look at
my width or height property" (which was temporarily done by
# flex-flow (Applies to: parent flex container element)
the main-size keyword until deprecated). The content
keyword means "size it based on the item's content" - this
This is a shorthand flex-direction and flex-wrap
keyword isn't well supported yet, so it's hard to test and harder
properties, which together define the flex container's main and
cross axes. Default is row nowrap .
to know what its brethren max-content , min-content , and
fit-content do.
CSS
flex-flow: <‘flex-direction’> || <‘flex-w
CSS
.item {
flex-basis: | auto; /* default
}
# justify-content
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flex-start
If set to 0 , the extra space around content isn't factored in. If
set to auto , the extra space is distributed based on its flexgrow value. See this graphic.
flex-end
# flex
center
This is the shorthand for flex-grow,
flex-shrink and
flex-basis combined. The second and third parameters
( flex-shrink and flex-basis ) are optional. Default is 0
1 auto .
space-between
CSS
space-around
.item {
flex: none | [ <'flex-grow'> <'flex-shr
}
space-evenly
It is recommended that you use this shorthand property
rather than set the individual properties. The short hand sets
the other values intelligently.
This defines the alignment along the main axis. It helps
distribute extra free space left over when either all the flex
items on a line are inflexible, or are flexible but have reached
their maximum size. It also exerts some control over the
# align-self
alignment of items when they overflow the line.
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CSS
flex-start
.container {
justify-content: flex-start | flex-end
}
flex-end
flex-start (default): items are packed toward the
start line
flex-end : items are packed toward to end line
center : items are centered along the line
space-between : items are evenly distributed in the
This allows the default alignment (or the one specified by
align-items ) to be overridden for individual flex items.
Please see the align-items explanation to understand the
available values.
line; first item is on the start line, last item on the end
line
CSS
space-around : items are evenly distributed in the line
with equal space around them. Note that visually the
.item {
spaces aren't equal, since all the items have equal space
on both sides. The first item will have one unit of space
against the container edge, but two units of space
align-self: auto | flex-start | flex-en
}
between the next item because that next item has its
own spacing that applies.
space-evenly : items are distributed so that the
spacing between any two items (and the space to the
Note that float , clear and vertical-align have no
effect on a flex item.
edges) is equal.
# align-items
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flex-start
flex-end
center
stretch
baseline
text text
text text
text text
text text
This defines the default behaviour for how flex items are laid
out along the cross axis on the current line. Think of it as the
justify-content version for the cross-axis (perpendicular
to the main-axis).
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CSS
.container {
align-items: flex-start | flex-end | ce
}
flex-start : cross-start margin edge of the items is
placed on the cross-start line
flex-end : cross-end margin edge of the items is
placed on the cross-end line
center : items are centered in the cross-axis
baseline : items are aligned such as their baselines
align
stretch (default): stretch to fill the container (still
respect min-width/max-width)
# align-content
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flex-start
flex-end
center
stretch
space-between
space-around
This aligns a flex container's lines within 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 there is only one line of
flex items.
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CSS
.container {
align-content: flex-start | flex-end |
}
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 around each line
stretch (default): lines stretch to take up the
remaining space
#
Examples
Let's start with a very very simple example, solving an almost daily problem: perfect centering. It
couldn't be any simpler if you use flexbox.
CSS
.parent {
display: flex;
height: 300px; /* Or whatever */
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}
.child {
width: 100px;
/* Or whatever */
height: 100px; /* Or whatever */
margin: auto;
/* Magic! */
}
This relies on the fact a margin set to `auto` in a flex container absorb extra space. So setting a
vertical margin of auto will make the item perfectly centered in both axis.
Now let's use some more properties. Consider a list of 6 items, all with a fixed dimensions in a matter
of aesthetics but they could be auto-sized. We want them to be evenly and nicely distributed on the
horizontal axis so that when we resize the browser, everything is fine (without media queries!).
CSS
.flex-container {
/* We first create a flex layout context */
display: flex;
/* Then we define the flow direction
and if we allow the items to wrap
* Remember this is the same as:
* flex-direction: row;
* flex-wrap: wrap;
*/
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flex-flow: row wrap;
/* Then we define how is distributed the remaining space */
justify-content: space-around;
}
Done. Everything else is just some styling concern. Below is a pen featuring this example. Be sure to go
to CodePen and try resizing your windows to see what happens.
HTML
SCSS
Result
Edit on
1
2
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5
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6
Let's try something else. Imagine we have a right-aligned navigation on the very top of our website, but
we want it to be centered on medium-sized screens and single-columned on small devices. Easy
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enough.
CSS
/* Large */
.navigation {
display: flex;
flex-flow: row wrap;
/* This aligns items to the end line on main-axis */
justify-content: flex-end;
}
/* Medium screens */
@media all and (max-width: 800px) {
.navigation {
/* When on medium sized screens, we center it by evenly distributing empty space around items
justify-content: space-around;
}
}
/* Small screens */
@media all and (max-width: 500px) {
.navigation {
/* On small screens, we are no longer using row direction but column */
flex-direction: column;
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}
}
HTML
SCSS
Result
Edit on
Home
About
Products
Contact
Let's try something even better by playing with flex items flexibility! What about a mobile-first 3columns layout with full-width header and footer. And independent from source order.
CSS
.wrapper {
display: flex;
flex-flow: row wrap;
}
/* We tell all items to be 100% width, via flex-basis */
.wrapper > * {
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flex: 1 100%;
}
/* We rely on source order for mobile-first approach
* in this case:
* 1. header
* 2. article
* 3. aside 1
* 4. aside 2
* 5. footer
*/
/* Medium screens */
@media all and (min-width: 600px) {
/* We tell both sidebars to share a row */
.aside { flex: 1 auto; }
}
/* Large screens */
@media all and (min-width: 800px) {
/* We invert order of first sidebar and main
* And tell the main element to take twice as much width as the other two sidebars
*/
.main { flex: 2 0px; }
.aside-1 { order: 1; }
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.main
{ order: 2; }
.aside-2 { order: 3; }
.footer
{ order: 4; }
}
HTML
CSS
EDIT
Result
ON
Header
Aside 1
Pellentesque habitant morbi tristique senectus et netus et
malesuada fames ac turpis egestas. Vestibulum tortor
quam, feugiat vitae, ultricies eget, tempor sit amet, ante.
Donec eu libero sit amet quam egestas semper. Aenean
ultricies mi vitae est. Mauris placerat eleifend leo.
Aside 2
Footer
▶ Prefixing Flexbox
▶ Related Properties
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▶
p
Other Resources
A Complete Guide to Flexbox | CSS-Tricks
▶ Bugs
#
Browser Support
Broken up by "version" of flexbox:
(new) means the recent syntax from the specification (e.g. display: flex; )
(tweener) means an odd unofficial syntax from 2011 (e.g. display: flexbox; )
(old) means the old syntax from 2009 (e.g. display: box; )
Chrome: 20- (old)
Safari: 3.1+ (old)
Firefox: 2-21 (old)
21+ (new)
6.1+ (new)
22+ (new)
Opera: 12.1+ (new)
IE: 10 (tweener)
Android: 2.1+ (old)
iOS: 3.2+ (old)
11+ (new)
4.4+ (new)
7.1+ (new)
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).
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