User CSS

Screenshot of User CSS extension showing the style manager

An extension for Safari 5 to Safari 11 that allows the user to override stylesheets for any web page with real-time updating of web pages. It is no longer maintained due to deprecation of JavaScript-based extensions starting with Safari 12.

The extension is licensed under MIT license.



Due to a limitation with Safari's URL parsing, domain wildcard only works for subdomains. For example, http://*.google.* will not work. You must use http://**

Database for User CSS is stored at ~/Library/Safari/LocalStorage. You can access this directory by pressing Cmd-Shift-G in Finder. The database file is named safari-extension_com.gridth.usercss-v892bvzc73_0.localstorage


Version 1.3.2
  • Safari 5.1 compatibility.
  • Fix interface glitch that cause item to be unselectable.
Version 1.3.1
  • Fix database corruption.
  • Ensure compatibility with other extension.
  • Minor usability additions.
Version 1.3
  • Interface redesign!
  • Slightly less ugly icon!
  • Initial fix for database corruption.
Version 1.2
  • Added an icon, albeit somewhat ugly.
  • Added settings to disable contextual menu.
  • Change to allow input fields to be resizable.
  • Fixed few typo into User CSS manager.
Version 1.1
  • Added support for secure sites.
  • Added domain exclusion to exclude domains from being matched.
  • Fixed a bug where rules with no trailing slash applies to all pages.
Version 1.0.1
  • Added toolbar button.
  • Added checkbox for enable/disable certain style.
  • Change to use Safari's resource for some UI elements.
Version 1.0
  • Initial release.