Draft:Userstyle

• Comment: I feel like this may be worth an article, but as of right now you are linking to user-generated sources (like forums) and extension store pages.
  Besides expanding this draft, you could always add the content into existing pages, for example Browser extension. EatingCarBatteries _{(contribs | talk)} 20:41, 15 June 2026 (UTC)

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For use of userstyles on Wikipedia, see Help:User style.

A userstyle (or user style) is a user-authored stylesheet, written in Cascading Style Sheets (CSS) or a CSS preprocessor language such as Stylus, Less, or Sass. Userstyles change the appearance of web pages in the user's browser (also known as skinning), primarily for the purposes of modifying color schemes, hiding unwanted elements (such as for ad blocking), or improving layouts and/or accessibility.

History

Userstyle functionality was historically included in major browser distributions through customization settings such as Firefox's userContent.css, Google Chrome's User StyleSheet/Custom.css, and Safari's advanced "Style sheet" setting. As most major browser distributions have since removed or phased out userstyles features, userstyles are now more often applied through userstyles managers.

Userstyle managers

A userstyle manager is a browser extension that provides a user interface to edit and organize userstyles. Userstyle managers perform a variety of functions, including but not limited to managing and syncing installed userstyles across browsers and profiles, checking for updates of installed userstyles, compiling stylesheets authored in preprocessor languages, injecting stylesheets into web pages, and patching browser security policies such as Content Security Policy to allow for userstyle functions.

Popular userstyle managers include Stylus,, xStyle, and Cascadea.

Stylish

Main article: Stylish (software)

The earliest known userstyle manager, Stylish, was the predominant userstyle manager from its inception in 2005 until the late-2010s.

Further information: Stylish (software) § Privacy issues

In 2018, it was revealed that that the extension had been collecting the complete web browsing history of its users without consent after an undisclosed sale of the extension two years earlier.

Userstyle repositories

Userstyles were historically shared and published in large centralized websites known as userstyle repositories. The now-defunct userstyles.org, also the homepage for the Stylish userstyles manager, was the first of such userstyles repositories and was popular during the 2010s.

Following the third-party acquisition of Stylish and userstyles.org in 2016, userstyles.org became increasingly inaccessible to users due to frequent downtime. As a result, archives of the site's content and user-submitted userstyles have been made to support continued usage of older userstyles. Since 2020, the userstyle repository userstyles.world has been popular among the userstyles community as an open source alternative.

Userstyles are often installed directly from software development version control platforms such as GitHub. Userstyle formats like UserCSS, which are installable directly from a file URL, have encouraged publishing through individual software repositories.

UserCSS

Some userstyle managers, namely Stylus and xStyle, support a specific format of userstyle known as UserCSS. UserCSS userstyles use a .user.css file extension, and include a metadata section at the top of the file noted with a special /* ==UserStyle== comment.

/* ==UserStyle==
@name         Example UserCSS style
@namespace    github.com/openstyles/stylus
@version      1.0.0
@license      unlicense
@preprocessor default
@var color link-color "Link Color" red
==/UserStyle== */

@-moz-document domain("example.com") {
  a {
    color: var(--link-color);
  }
}

UserCSS metadata may include the following fields, though there is no definitive specification for the UserCSS metadata format and userstyle managers may differ in support.

@name

The name of the userstyle.

@namespace

The namespace of the userstyle. The combination of @name and @namespace must be unique for each userstyle. Used to help distinguish between userstyles with the same name. Usually consists of the author's nickname or homepage, often in the form of a URL.

@version

The version of the userstyle. The field is typically considered required by userstyle managers, and is considered when checking for updates to the userstyle. Usually in the SemVer (semantic versioning) format.

@description

A description of the userstyle.

@author

The author of the userstyle. Consists of the author's name and optionally an associated email or URL.

@homepageURL

The homepage URL of the userstyle.

@supportURL

The support URL of the userstyle, to provide users with a link to give feedback to the author.

@updateURL

The update URL of the userstyle. Consists of a URL to a userstyle file, used to compare against for updates. When not defined, the userstyle is updated from the original URL used for installation, if any.

@license

The license of the userstyle in the SPDX license identifier format.

@preprocessor

The preprocessor of the userstyle, such as Stylus, Less, or Sass. When undefined, standard CSS syntax is assumed.

@var

Used to define user options for the userstyle. May support a variety of types, such as for text, numbers, colors, toggles, and selecting from predefined options.

See also

• Stylus (browser extension)
• Stylish (software)
• Userscript