content
Baseline Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.
The content
CSS property replaces content with a generated value. It can be used to define what is rendered inside an element or pseudo-element. For elements, the content
property specifies whether the element renders normally (normal
or none
) or is replaced with an image (and associated "alt" text). For pseudo-elements and margin boxes, content
defines the content as images, text, both, or none, which determines whether the element renders at all.
Objects inserted using the content
property are anonymous replaced elements.
Try it
Syntax
/* Keywords that cannot be combined with other values */
content: normal;
content: none;
/* <content-replacement>: <image> values */
content: url("http://www.example.com/test.png");
content: linear-gradient(#e66465, #9198e5);
content: image-set("image1x.png" 1x, "image2x.png" 2x);
/* speech output: alternative text after a "/" */
content: url("../img/test.png") / "This is the alt text";
/* <string> value */
content: "unparsed text";
/* <counter> values, optionally with <list-style-type> */
content: counter(chapter_counter);
content: counter(chapter_counter, upper-roman);
content: counters(section_counter, ".");
content: counters(section_counter, ".", decimal-leading-zero);
/* attr() value linked to the HTML attribute value */
content: attr(href);
/* <quote> values */
content: open-quote;
content: close-quote;
content: no-open-quote;
content: no-close-quote;
/* <content-list>: a list of content values.
Several values can be used simultaneously */
content: "prefix" url(http://www.example.com/test.png);
content: "prefix" url("/img/test.png") "suffix" / "Alt text";
content: open-quote counter(chapter_counter);
/* Global values */
content: inherit;
content: initial;
content: revert;
content: revert-layer;
content: unset;
Values
The value can be:
- One of two keywords —
none
ornormal
. <content-replacement>
when replacing a DOM node.<content-replacement>
is always an<image>
.- A
<content-list>
when replacing pseudo-elements and margin boxes. A<content-list>
is a list of one or more anonymous inline boxes appearing in the order specified. Each<content-list>
item is of type<string>
,<image>
,<counter>
,<quote>
,<target>
, or<leader()>
. - An optional alternative text value of a
<string>
or<counter>
, preceded by a slash (/
).
The keywords and data types mentioned above are described in more detail below:
none
-
When applied to a pseudo-element, the pseudo-element is not generated. When applied to an element, the value has no effect.
normal
-
The default value. Computes to
none
for the::before
and::after
pseudo-elements. For other pseudo-elements, the content will be the initial (or normal) content expected for that::marker
,::placeholder
, or::file-selector-button
. For regular elements or page margin boxes, this computes to the element's descendants. <string>
-
A sequence of characters enclosed in matching single or double quotes. Multiple string values will be concatenated (there is no concatenation operator in CSS).
<image>
-
An
<image>
, representing an image to display. This can be equal to a<url>
,image-set()
, or<gradient>
data type, or a part of the webpage itself, defined by theelement()
function. <counter>
-
The
<counter>
value is a CSS counter, generally a number produced by computations defined by<counter-reset>
and<counter-increment>
properties. It can be displayed using either thecounter()
orcounters()
function.counter()
-
The
counter()
function has two forms: 'counter(name)' or 'counter(name, style)'. The generated text is the value of the innermost counter of the given name in scope at the given pseudo-element. It is formatted in the specified<list-style-type>
(decimal
by default). counters()
-
The
counters()
function also has two forms: 'counters(name, string)' or 'counters(name, string, style)'. The generated text is the value of all counters with the given name in scope at the given pseudo-element, from outermost to innermost, separated by the specified string. The counters are rendered in the indicated<list-style-type>
(decimal
by default).
<quote>
-
The
<quote>
data type includes language- and position-dependent keywords:open-quote
andclose-quote
-
These values are replaced by the appropriate string from the
quotes
property. no-open-quote
andno-close-quote
-
Introduces no content, but increments (decrements) the level of nesting for quotes.
<target>
-
The
<target>
data type includes three target functions,<target-counter()>
,<target-counters()>
, and<target-text()>
that create cross-references obtained from the target end of a link. See Formal syntax. <leader()>
-
The
<leader()>
data type includes a leader function:leader( <leader-type> )
. This function accepts the keyword valuesdotted
,solid
, orspace
(equal toleader(".")
,leader("_")
, andleader(" ")
, respectively), or a<string>
as a parameter. When supported and used as a value forcontent
, the leader-type provided will be inserted as a repeating pattern, visually connecting content across a horizontal line. attr(x)
-
The
attr(x)
CSS function retrieves the value of an attribute of the selected element, or the pseudo-element's originating element. The value of the element's attributex
is an unparsed string representing the attribute name. If there is no attributex
, an empty string is returned. The case sensitivity of the attribute name parameter depends on the document language. - alternative text:
/ <string> | <counter>
-
Alternative text may be specified for an image or any
<content-list>
items, by appending a forward slash and then a string of text or a counter. The alternative text is intended for speech output by screen-readers, but may also be displayed in some browsers. Note that if the browser does not support alternative text, thecontent
declaration will be considered invalid and will be ignored. The/ <string>
or/ <counter>
data types specify the "alt text" for the element.
Formal definition
Initial value | normal |
---|---|
Applies to | All elements, tree-abiding pseudo-elements, and page margin boxes |
Inherited | no |
Computed value | On elements, always computes to normal . On ::before and ::after , if normal is specified, computes to none . Otherwise, for URI values, the absolute URI; for attr() values, the resulting string; for other keywords, as specified. |
Animation type | discrete |
Formal syntax
content =
normal |
none |
[ <content-replacement> | <content-list> ] [ / [ <string> | <counter> | <attr()> ]+ ]? |
<element()>
<content-replacement> =
<image>
<content-list> =
[ <string> | <counter()> | <counters()> | <content()> | <attr()> ]+
<counter> =
<counter()> |
<counters()>
<attr()> =
attr( <attr-name> <attr-type>? , <declaration-value>? )
<element()> =
element( <id-selector> )
<image> =
<url> |
<gradient>
<counter()> =
counter( <counter-name> , <counter-style>? )
<counters()> =
counters( <counter-name> , <string> , <counter-style>? )
<content()> =
content( [ text | before | after | first-letter | marker ]? )
<attr-name> =
[ <ident-token> '|' ]? <ident-token>
<attr-type> =
string |
ident |
color |
number |
percentage |
length |
angle |
time |
frequency |
flex |
<dimension-unit>
<id-selector> =
<hash-token>
<url> =
<url()> |
<src()>
<counter-style> =
<counter-style-name> |
<symbols()>
<url()> =
url( <string> <url-modifier>* ) |
<url-token>
<src()> =
src( <string> <url-modifier>* )
<symbols()> =
symbols( <symbols-type>? [ <string> | <image> ]+ )
<symbols-type> =
cyclic |
numeric |
alphabetic |
symbolic |
fixed
Accessibility
CSS-generated content is not included in the DOM. Because of this, it will not be represented in the accessibility tree and certain assistive technology/browser combinations will not announce it. If the content conveys information that is critical to understanding the page's purpose, it is better to include it in the main document.
If inserted content is not decorative, check that the information is provided to assistive technologies and is also available when CSS is turned off.
- Accessibility support for CSS generated content – Tink (2015)
- WCAG, Guideline 1.3: Create content that can be presented in different ways
- Understanding Success Criterion 1.3.1 | W3C Understanding WCAG 2.0
- Failure of Success Criterion 1.3.1: inserting non-decorative generated content Techniques for WCAG 2.0
Examples
The first five examples create generated content on pseudo-elements. The last three are examples of element replacement.
Appending strings based on an element's class
This example inserts generated text after the text of elements that have a particular class name. The text is colored red.
HTML
<h2>Paperback Best Sellers</h2>
<ol>
<li>Political Thriller</li>
<li class="new-entry">Halloween Stories</li>
<li>My Biography</li>
<li class="new-entry">Vampire Romance</li>
</ol>
CSS
.new-entry::after {
content: " New!"; /* The leading space creates separation
between the DOM node's content and the generated content
being added. */
color: red;
}
Result
Quotes
This example inserts differently colored quotation marks around quotes.
HTML
<p>
According to Sir Tim Berners-Lee,
<q cite="http://www.w3.org/People/Berners-Lee/FAQ.html#Internet">
I was lucky enough to invent the Web at the time when the Internet already
existed - and had for a decade and a half.
</q>
We must understand that there is nothing fundamentally wrong with building on
the contributions of others.
</p>
<p lang="fr-fr">
Mais c'est Magritte qui a dit,
<q lang="fr-fr"> Ceci n'est pas une pipe. </q>.
</p>
CSS
q {
color: #00f;
}
q::before,
q::after {
font-size: larger;
color: #f00;
background: #ccc;
}
q::before {
content: open-quote;
}
q::after {
content: close-quote;
}
Result
Note the type of quotes generated is based on the language. Browsers add open- and close-quotes before and after <q>
elements by default, so the quotes in this example would appear without them being explicitly set. They could have been turned off by setting the respective content
property values to no-open-quote
and no-close-quote
, or by setting them both to none
. They can also be turned off by setting the quotes
property to none
instead.
Adding text to list item counters
This example combines a counter sandwiched between two <string>
s prepended to all list items, creating a more detailed marker for list items (<li>
) within unordered lists (<ol>
).
HTML
<ol>
<li>Dogs</li>
<li>Cats</li>
<li>
Birds
<ol>
<li>Owls</li>
<li>Ducks</li>
<li>Flightless</li>
</ol>
<li>Marsupials</li>
</li>
</ol>
CSS
ol {
counter-reset: items;
margin-left: 2em;
}
li {
counter-increment: items;
}
li::marker {
content: "item " counters(items, ".", numeric) ": ";
}
Result
The generated content on each list item's marker adds the text "item " as a prefix, including a space to separate the prefix from the counter, which is followed by ": ", a colon and an additional space. The counters()
function defines a numeric items
counter, in which the numbers of nested ordered lists have their numbers separated with a period (.
) in most browsers.
Strings with attribute values
This example is useful for print stylesheets. It uses an attribute selector to select every fully qualified secure link, adding the value of the href
attribute after the link text as the content of the ::after
pseudo-element.
HTML
<ul>
<li><a href="https://mozilla.com">Mozilla</a></li>
<li><a href="/">MDN</a></li>
<li><a href="https://openwebdocs.org">OpenWebDocs</a></li>
</ul>
CSS
a[href^="https://"]::after
{
content: " (URL: " attr(href) ")";
color: darkgreen;
}
Result
The generated content is the value of the href
attribute, prepended by "URL: ", with a space, all in parentheses.
Adding an image with alternative text
This example inserts an image before all links. Two content
values are provided. The later content
value includes an image with alternative text that a screen reader can output as speech. If a browser does not support alternative text, this declaration will be considered invalid, with the previous content
value displaying. This fallback content list includes an image and the message " - alt text is not supported - ".
HTML
<a href="https://www.mozilla.org/en-US/">Mozilla Home Page</a>
CSS
The CSS to show the image and set the alternative text is shown below.
This also sets the font and color for the content.
This will be used on browsers that display the alternative text and in browsers that don't support alternative text and show the fallback content
value.
a::before {
/* fallback content */
content: url("https://mozorg.cdn.mozilla.net/media/img/favicon.ico")
" - alt text is not supported - ";
/* content with alternative text */
content: url("https://mozorg.cdn.mozilla.net/media/img/favicon.ico") /
" MOZILLA: ";
font:
x-small Arial,
sans-serif;
color: gray;
}
Result
Note: If the alternative text syntax is supported, the value will be exposed in the browser's accessibility tree. Refer to the See also section for browser-specific accessibility panels.
If using a screen reader, it should speak the word "MOZILLA" when it reaches the image. If supported (if the "alt text is not supported" is not showing), you can select the ::before
pseudo-element with your developer tools selection tool, and view the accessible name in the accessibility panel.
In browsers that don't support the alternative text syntax the whole declaration containing the alt text is invalid. In this case, the previous content
value will be used, showing the image and "alt text is not supported" text.
Element replacement with URL
This example replaces a regular element! The element's contents are replaced with an SVG using the <url>
type.
Pseudo-elements aren't rendered on replaced elements. As this element is replaced, any matching ::after
or ::before
are not generated or applied. To demonstrate this, we include an ::after
declaration block, attempting to add the id
as generated content. This pseudo-element will not be generated as the element is replaced.
HTML
<div id="replaced">This content is replaced!</div>
CSS
#replaced {
content: url("mdn.svg");
}
/* will not show if element replacement is supported */
div::after {
content: " (" attr(id) ")";
}
Result
When generating content on regular elements (rather than just on pseudo-elements), the entire element is replaced. This means that ::before
and ::after
pseudo-elements are not generated.
Element replacement with <gradient>
This example demonstrates how an element's contents can be replaced by any type of <image>
, in this case, a CSS gradient. The element's contents are replaced with a linear-gradient()
. With @supports
, we provide alt text support and a repeating-linear-gradient()
for browsers that support alt text with element content replacement.
HTML
<div id="replaced">I disappear</div>
CSS
div {
border: 1px solid;
background-color: #ccc;
min-height: 100px;
min-width: 100px;
}
#replaced {
content: linear-gradient(#639f, #c96a);
}
@supports (content: linear-gradient(#000, #fff) / "alt text") {
#replaced {
content: repeating-linear-gradient(blue 0, orange 10%) /
"Gradients and alt text are supported";
}
}
Result
Check the browser compatibility chart. All browsers support gradients and all browsers support replacing elements with images, but not all browsers support gradients as a content
value and not all browsers support alt text on replacements. If the browser displays a box with no gradient, replacing elements is supported, but gradients are not supported as a content replacement value. If the element is replaced with a striped gradient, the browser supports both.
Element replacement with image-set()
This example replaces an element's content with a image-set()
. If the users display has normal resolution the 1x.png
will be displayed screens with a higher resolution will display the 2x.png
image.
HTML
<div id="replaced">Mozilla</div>
CSS
#replaced {
content: image-set(
"1x.png" 1x,
"2x.png" 2x
);
}
Result
Specifications
Specification |
---|
CSS Generated Content Module Level 3 # content-property |
Browser compatibility
BCD tables only load in the browser
See also
::after
::before
::marker
contain
quotes
<gradient>
image-set()
<url>
-
CSS generated content module
-
CSS lists and counters module
-
Browser accessibility panels: Firefox Accessibility inspector, Chrome Accessibility pane, and Safari Accessibility tree