@document

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;
  }
}

Syntax

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 \\.).

@document is currently only supported in Firefox; if you wanted to replicate using such functionality in your own non-Firefox browser, you could try using this polyfill by @An-Error94, which uses a combination of a user script, data-* attributes, and attribute selectors.

Formal syntax

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

Examples

Specifying document for CSS rule

@document url("http://www.w3.org/"),
          url-prefix("http://www.w3.org/Style/"),
          domain("mozilla.org"),
          media-document("video"),
          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;
  }
}

Specifications

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

Browser compatibility

See also

• Per-site user style sheet rules on the www-style mailing list.