The content CSS property is used with the ::before and ::after pseudo-elements to generate content in an element. Objects inserted using the content property are anonymous replaced elements.
/* Keywords that cannot be combined with other values */
content: normal;
content: none;
/* <string> value, non-latin characters must be encoded */
/* e.g. \00A0 for   */
content: "prefix";
/* <url> value */
content: url("http://www.example.com/test.png");
/* <counter> values */
content: counter(chapter_counter);
content: counters(section_counter, ".");
/* attr() value linked to the HTML attribute value */
content: attr(value string);
/* Language- and position-dependent keywords */
content: open-quote;
content: close-quote;
content: no-open-quote;
content: no-close-quote;
/* Except for normal and none, several values */
/* can be used simultaneously */
content: open-quote chapter_counter;
/* Global values */
content: inherit;
content: initial;
content: unset;
| Initial value | normal | 
|---|---|
| Applies to | ::beforeand::afterpseudo-elements | 
| Inherited | no | 
| Media | all | 
| Computed value | On elements, always computes to normal. On::beforeand::after, ifnormalis specified, computes tonone. Otherwise, for URI values, the absolute URI; forattr()values, the resulting string; for other keywords, as specified. | 
| Animation type | discrete | 
| Canonical order | the unique non-ambiguous order defined by the formal grammar | 
Syntax
Values
- none
- The pseudo-element is not generated.
- normal
- Computes to nonefor the::beforeand::afterpseudo-elements.
- <string>
- One or more text characters.
- <url>
- A URL that designates an external resource (such as an image). If the resource can't be displayed, it is either ignored or a placeholder is shown.
- <counter>
- The value of a CSS counter, generally a number. It can be displayed using either the counter()orcounters()function.
- 
 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 style (decimalby default).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 style (decimalby default).
- attr(x)
- The value of the element's attribute xas a string. If there is no attributex, an empty string is returned. The case-sensitivity of attribute names depends on the document language.
- open-quote|- close-quote
- These values are replaced by the appropriate string from the quotesproperty.
- no-open-quote|- no-close-quote
- Introduces no content, but increments (decrements) the level of nesting for quotes.
Formal syntax
normal | none | [ <content-replacement> | <content-list> ] [/ <string> ]?where
<content-replacement> = <image>
<content-list> = [ <string> | contents | <image> | <quote> | <target> | <leader()> ]+where
<image> = <url> | <image()> | <image-set()> | <element()> | <cross-fade()> | <gradient>
<quote> = open-quote | close-quote | no-open-quote | no-close-quote
<target> = <target-counter()> | <target-counters()> | <target-text()>
<leader()> = leader( <leader-type> )where
<image()> = image( [ [ <image> | <string> ]? , <color>? ]! )
<image-set()> = image-set( <image-set-option># )
<element()> = element( <id-selector> )
<cross-fade()> = cross-fade( <cf-mixing-image> , <cf-final-image>? )
<gradient> = <linear-gradient()> | <repeating-linear-gradient()> | <radial-gradient()> | <repeating-radial-gradient()>
<target-counter()> = target-counter( [ <string> | <url> ] , <custom-ident> , <counter-style>? )
<target-counters()> = target-counters( [ <string> | <url> ] , <custom-ident> , <string> , <counter-style>? )
<target-text()> = target-text( [ <string> | <url> ] , [ content | before | after | first-letter ]? )
<leader-type> = dotted | solid | space | <string>where
<color> = <rgb()> | <rgba()> | <hsl()> | <hsla()> | <hex-color> | <named-color> | currentcolor | <deprecated-system-color>
<image-set-option> = [ <image> | <string> ] <resolution>
<cf-mixing-image> = <percentage>? && <image>
<cf-final-image> = <image> | <color>
<linear-gradient()> = linear-gradient( [ <angle> | to <side-or-corner> ]? , <color-stop-list> )
<repeating-linear-gradient()> = repeating-linear-gradient( [ <angle> | to <side-or-corner> ]? , <color-stop-list> )
<radial-gradient()> = radial-gradient( [ <ending-shape> || <size> ]? [ at <position> ]? , <color-stop-list> )
<repeating-radial-gradient()> = repeating-radial-gradient( [ <ending-shape> || <size> ]? [ at <position> ]? , <color-stop-list> )
<counter-style> = <counter-style-name> | symbols()where
<rgb()> = rgb( [ [ <percentage>{3} | <number>{3} ] [ / <alpha-value> ]? ] | [ [ <percentage>#{3} | <number>#{3} ] , <alpha-value>? ] )
<rgba()> = rgba( [ [ <percentage>{3} | <number>{3} ] [ / <alpha-value> ]? ] | [ [ <percentage>#{3} | <number>#{3} ] , <alpha-value>? ] )
<hsl()> = hsl( [ <hue> <percentage> <percentage> [ / <alpha-value> ]? ] | [ <hue>, <percentage>, <percentage>, <alpha-value>? ] )
<hsla()> = hsla( [ <hue> <percentage> <percentage> [ / <alpha-value> ]? ] | [ <hue>, <percentage>, <percentage>, <alpha-value>? ] )
<side-or-corner> = [ left | right ] || [ top | bottom ]
<color-stop-list> = <color-stop>#{2,}
<ending-shape> = circle | ellipse
<size> = closest-side | farthest-side | closest-corner | farthest-corner | <length> | <length-percentage>{2}
<position> = [[ left | center | right | top | bottom | <length-percentage> ] | [ left | center | right | <length-percentage> ] [ top | center | bottom | <length-percentage> ] | [ center | [ left | right ] <length-percentage>? ] && [ center | [ top | bottom ] <length-percentage>? ]]
<counter-style-name> = <custom-ident>where
<alpha-value> = <number> | <percentage>
<hue> = <number> | <angle>
<color-stop> = <color> <length-percentage>?
<length-percentage> = <length> | <percentage>
Examples
Headings and quotes
This example inserts quotation marks around quotes, and adds the word "Chapter" before headings.
HTML
<h1>5</h1>
<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>
<h1>6</h1>
<p>According to the Mozilla Manifesto,
  <q cite="http://www.mozilla.org/en-US/about/manifesto/">Individuals
    must have the ability to shape the Internet and
    their own experiences on the Internet.</q>
  Therefore, we can infer that contributing to the open web
  can protect our own individual experiences on it.
</p>
CSS
q {
  color: blue;
}
q::before {
  content: open-quote;
}
q::after {
  content: close-quote;
}
h1::before  {
  content: "Chapter ";  /* The trailing space creates separation
                           between the added content and the
                           rest of the content */
}
Result
Image combined with text
This example inserts an image before the link. If the image is not found, it inserts text instead.
HTML
<a href="http://www.mozilla.org/en-US/">Mozilla Home Page</a>
CSS
a::before {
  content: url("https://mozorg.cdn.mozilla.net/media/img/favicon.ico") " MOZILLA: ";
  font: x-small Arial, sans-serif;
  color: gray;
}
Result
Targeting classes
This example inserts additional text after special items in a list.
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 added content and the
                        rest of the content */
  color: red;
}
Result
Images and element attributes
This example inserts an image before each link, and adds its id attribute after.
HTML
<ul>
  <li><a id="moz" href="http://www.mozilla.org/">
    Mozilla Home Page</a></li>
  <li><a id="mdn" href="https://developer.mozilla.org/">
    Mozilla Developer Network</a></li>
</ul>
CSS
a {
  text-decoration: none;
  border-bottom: 3px dotted navy;
}
a::after {
  content: " (" attr(id) ")";
}
#moz::before {
  content: url("https://mozorg.cdn.mozilla.net/media/img/favicon.ico") ;
}
#mdn::before {
  content: url("https://mdn.mozillademos.org/files/7691/mdn-favicon16.png") ;
}
li {
  margin: 1em;
}
Result
Specifications
| Specification | Status | Comment | 
|---|---|---|
| CSS Generated Content Module Level 3 The definition of 'content' in that specification. | Working Draft | |
| CSS Level 2 (Revision 1) The definition of 'content' in that specification. | Recommendation | Initial definition | 
Browser compatibility
| Feature | Chrome | Edge | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) | 
|---|---|---|---|---|---|---|
| Basic support | 1.0 | (Yes) | 1.0 (1.7 or earlier) | 8.0 | 4.0 | 1.0 | 
| url()support | 1.0 | ? | 1.0 (1.7 or earlier) | 8.0 | 7.0 | 1.0 | 
| Feature | Android | Edge | Firefox Mobile (Gecko) | IE Phone | Opera Mobile | Safari Mobile | 
|---|---|---|---|---|---|---|
| Basic support | 1.0 | (Yes) | 1.0 (1.0) | 8.0 | 9.5 | 1.0 | 
| url()support | ? | ? | ? | ? | ? | ? |