@container
The @container
CSS at-rule is a conditional group rule that applies styles to a containment context.
Style declarations are filtered by a condition and applied to the container if the condition is true.
The condition is evaluated when the container changes size.
An optional case-sensitive container-name
can be provided which filters the set of query containers considered to just those with a matching query container name.
Once an eligible query container has been selected for an element, each container feature in the <container-condition>
is evaluated against that query container.
Syntax
The @container
at-rule has the following syntax:
@container <container-condition> { <stylesheet> }
For example:
css
@container (width > 400px) {
h2 {
font-size: 1.5em;
}
}
Values
<container-condition>
-
A set of features that are evaluated against the query container when the size of the container changes. Styles defined in the
<stylesheet>
are applied if the condition is true. <stylesheet>
-
A set of CSS declarations.
Logical keywords in container queries
Logical keywords can be used to define the container condition:
and
combines two or more conditions.or
combines two or more conditions.not
negates the condition. Only one 'not' condition is allowed per container query and cannot be used with theand
oror
keywords.
css
@container not (width < 400px) {
/* <stylesheet> */
}
@container (width > 400px) and (height > 400px) {
/* <stylesheet> */
}
@container (width > 400px) or (height > 400px) {
/* <stylesheet> */
}
@container (width > 400px) not (height > 400px) {
/* <stylesheet> */
}
Named containment contexts
A containment context can be named using the container-name
property.
css
.post {
container-name: sidebar;
container-type: inline-size;
}
The shorthand syntax for this is to use container
in the form container: <name> / <type>
, for example:
css
.post {
container: sidebar / inline-size;
}
In container queries, the container-name
property is used to filter the set of containers to those with a matching query container name:
css
@container sidebar (width > 400px) {
/* <stylesheet> */
}
Details about usage and naming restrictions are described in the container-name
page.
Descriptors
The following descriptors can be used within the container condition:
aspect-ratio
-
The
aspect-ratio
of the container calculated as the width to the height of the container expressed as a<ratio>
value. block-size
-
The
block-size
of the container expressed as a<length>
value. height
-
The height of the container expressed as a
<length>
value. inline-size
-
The
inline-size
of the container expressed as a<length>
value. orientation
-
The orientation of the container, either
landscape
orportrait
. width
-
The width of the container expressed as a
<length>
value.
Examples
Setting styles based on a container's size
Consider the following example of a card component with a title and some text:
html
<div class="post">
<div class="card">
<h2>Card title</h2>
<p>Card content</p>
</div>
</div>
A container context can be created using the container-type
property, in this case using the inline-size
value on the .post
class.
You can then use the @container
at-rule to apply styles to the element with the .card
class in a container that's narrower than 650px
.
css
/* A container context based on inline size */
.post {
container-type: inline-size;
}
/* Apply styles if the container is narrower than 650px */
@container (width < 650px) {
.card {
width: 50%;
background-color: gray;
font-size: 1em;
}
}
Creating named container contexts
Given the following HTML example which is a card component with a title and some text:
html
<div class="post">
<div class="card">
<h2>Card title</h2>
<p>Card content</p>
</div>
</div>
First, create a container context using the container-type
and container-name
properties.
The shorthand syntax for this declaration is described in the container
page.
css
.post {
container-type: inline-size;
container-name: summary;
}
Next, target that container by adding the name to the container query:
css
@container summary (min-width: 400px) {
.card {
font-size: 1.5em;
}
}
Nested container queries
It's not possible to target multiple containers in a single container query. It is possible to nest container queries which has the same effect.
The following query evaluates to true and applies the declared style if the container named summary
is wider than 400px
and has an ancestor container wider than 800px
:
css
@container summary (min-width: 400px) {
@container (min-width: 800px) {
/* <stylesheet> */
}
}
Specifications
Specification |
---|
CSS Containment Module Level 3 # container-rule |
Browser compatibility
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