A propriedade flex do CSS, define como um ítem será posicionado para no espaço disponível dentro de seu container.
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Propriedades
Esta propriedade é uma abreviação das seguintes propriedades CSS:
<div class="flex-container">
<div class="item auto">auto</div>
<div class="item auto">auto</div>
<div class="item auto">auto</div>
</div>
<div class="flex-container">
<div class="item auto">auto</div>
<div class="item initial">initial</div>
<div class="item initial">initial</div>
</div>
<div class="flex-container">
<div class="item auto">auto</div>
<div class="item auto">auto</div>
<div class="item none">none</div>
</div>
<div class="flex-container">
<div class="item initial">initial</div>
<div class="item none">none</div>
<div class="item none">none</div>
</div>
<div class="flex-container">
<div class="item four">4</div>
<div class="item two">2</div>
<div class="item one">1</div>
</div>
* {
box-sizing: border-box;
}
.flex-container {
background-color: #F4F7F8;
resize: horizontal;
overflow: hidden;
display: flex;
margin: 1em;
}
.item {
margin: 1em;
padding: 0.5em;
width: 110px;
min-width: 0;
background-color: #1B5385;
color: white;
font-family: monospace;
font-size: 13px;
}
.initial {
flex: initial;
}
.auto {
flex: auto;
}
.none {
flex: none;
}
.four {
flex: 4;
}
.two {
flex: 2;
}
.one {
flex: 1;
}
By default flex items don't shrink below their minimum content size. To change this, set the item's min-width
or min-height
.
Sintaxe
/* Propriedades principais */
flex: auto;
flex: initial;
flex: none;
/* Valor único, sem unidade: flex-grow */
flex: 2;
/* Valor único, unidade width/height: flex-basis */
flex: 10em;
flex: 30%;
flex: min-content;
/* Dois valores: flex-grow | flex-basis */
flex: 1 30px;
/* Dois valores: flex-grow | flex-shrink */
flex: 2 2;
/* Três valores: flex-grow | flex-shrink | flex-basis */
flex: 2 2 10%;
/* Valores globais */
flex: inherit;
flex: initial;
flex: unset;
The flex
property may be specified using one, two, or three values.
- One-value syntax: the value must be one of:
- a
<number>
: In this case it is interpreted asflex: <number> 1 0
; the<flex-shrink>
value is assumed to be 1 and the<flex-basis>
value is assumed to be0
. - one of the keywords:
none
,auto
, orinitial
.
- a
- Two-value syntax: the first value must be a
<number>
and it is interpreted as<flex-grow>
. The second value must be one of:- a
<number>
: then it is interpreted as<flex-shrink>
. - a valid value for
width
: then it is interpreted as<flex-basis>
.
- a
- Three-value syntax: the values must be in the following order:
- a
<number>
for<flex-grow>
. - a
<number>
for<flex-shrink>
. - a valid value for
width
for<flex-basis>
.
- a
Values
initial
- The item is sized according to its
width
andheight
properties. It shrinks to its minimum size to fit the container, but does not grow to absorb any extra free space in the flex container. This is equivalent to setting "flex: 0 1 auto
". auto
- The item is sized according to its
width
andheight
properties, but grows to absorb any extra free space in the flex container, and shrinks to its minimum size to fit the container. This is equivalent to setting "flex: 1 1 auto
". none
- The item is sized according to its
width
andheight
properties. It is fully inflexible: it neither shrinks nor grows in relation to the flex container. This is equivalent to setting "flex: 0 0 auto
". <'flex-grow'>
- Defines the
flex-grow
of the flex item. Negative values are considered invalid. Defaults to1
when omitted. <'flex-shrink'>
- Defines the
flex-shrink
of the flex item. Negative values are considered invalid. Defaults to1
when omitted. <'flex-basis'>
- Defines the
flex-basis
of the flex item. A preferred size of0
must have a unit to avoid being interpreted as a flexibility. Defaults to0
when omitted.
Formal syntax
Example
#flex-container {
display: flex;
flex-direction: row;
}
#flex-container > .flex-item {
flex: auto;
}
#flex-container > .raw-item {
width: 5rem;
}
<div id="flex-container">
<div class="flex-item" id="flex">Flex box (click to toggle raw box)</div>
<div class="raw-item" id="raw">Raw box</div>
</div>
var flex = document.getElementById("flex");
var raw = document.getElementById("raw");
flex.addEventListener("click", function() {
raw.style.display = raw.style.display == "none" ? "block" : "none";
});
#flex-container {
width: 100%;
font-family: Consolas, Arial, sans-serif;
}
#flex-container > div {
border: 1px solid #f00;
padding: 1rem;
}
#flex-container > .raw-item {
border: 1px solid #000;
}
Result
Specifications
Specification | Status | Comment |
---|---|---|
CSS Flexible Box Layout Module The definition of 'flex' in that specification. |
Candidata a Recomendação | Initial definition |
Initial value | as each of the properties of the shorthand:
|
---|---|
Aplica-se a | flex items, including in-flow pseudo-elements |
Inherited | não |
Computed value | as each of the properties of the shorthand:
|
Animation type | as each of the properties of the shorthand:
|
Browser compatibility
BCD tables only load in the browser
The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
See also
- CSS Flexbox Guide: Basic Concepts of Flexbox
- CSS Flexbox Guide: Controlling Ratios of flex items along the main axis