This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The @document CSS at-rule restricts the style rules contained within it based on the URL of the document. It is designed primarily for user-defined style sheets, though it can be used on author-defined style sheets, too.

@document url("https://www.example.com/") {
  h1 {
    color: green;


An @document rule can specify one or more matching functions. If any of the functions apply to a given URL, the rule will take effect on that URL. The functions available are:

  • url(), which matches an exact URL.
  • url-prefix(), which matches if the document URL starts with the value provided.
  • domain(), which matches if the document URL is on the domain provided (or a subdomain of it).
  • media-document(), with the parameter of video, image, plugin or all.
  • regexp(), which matches if the document URL is matched by the regular expression provided. The expression must match the entire URL.

The values provided to the url(), url-prefix(), domain(), and media-document() functions can be optionally enclosed by single or double quotes. The values provided to the regexp() function must be enclosed in quotes.

Escaped values provided to the regexp() function must additionally be escaped from the CSS. For example, a . (period) matches any character in regular expressions. To match a literal period, you would first need to escape it using regular expression rules (to \.), then escape that string using CSS rules (to \\.).

Note: There is a -moz-prefixed version of this property — @-moz-document. This has been limited to use only in user and UA sheets in Firefox 59 in Nightly and Beta — an experiment designed to mitigate potential CSS injection attacks (bug 1035091).

Formal syntax

@document [ <url> | url-prefix(<string>) | domain(<string>) | media-document(<string>) | regexp(<string>) ]# {



@document url(http://www.w3.org/),
          regexp("https:.*") {
  /* CSS rules here apply to:
     - The page "http://www.w3.org/"
     - Any page whose URL begins with "http://www.w3.org/Style/"
     - Any page whose URL's host is "mozilla.org"
       or ends with ".mozilla.org"
     - Any standalone video
     - Any page whose URL starts with "https:" */

  /* Make the above-mentioned pages really ugly */
  body {
    color: purple;
    background: yellow;


Initially in CSS Conditional Rules Module Level 3, @document has been postponed to Level 4.

Browser compatibilityUpdate compatibility data on GitHub

Chrome Edge Firefox Internet Explorer Opera Safari
Basic support No ? 61
Prefixed Disabled
Prefixed Disabled
Prefixed Implemented with the vendor prefix: -moz-
Disabled by default in web pages, except for an empty url-prefix() value, which is supported due to its use in Firefox browser detection. Still supported in user stylesheets.
Disabled From version 61: this feature is behind the layout.css.moz-document.content.enabled preference (needs to be set to true). To change preferences in Firefox, visit about:config.
1.5 — 61
Prefixed Implemented with the vendor prefix: -moz-
No No No
regexp() No ? 6 No No No
Android webview Chrome for Android Edge Mobile Firefox for Android Opera for Android iOS Safari Samsung Internet
Basic support ? ? ? ? ? ? No
regexp() No No ? ? No No No

See also

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