Style Engine – Custom CSS & JavaScript Firefox

Style Engine – Custom CSS & JavaScript

Apply custom CSS and JavaScript to websites globally or per domain. Lightweight, local-only, and fully user-controlled.
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Features & Capabilities

Style Engine lets you apply your own CSS and JavaScript rules to websites. Built for developers, designers, and power users who want precise UI control without touching server-side code.

Apply custom CSS and JavaScript to websites globally or per domain. Lightweight, local-only, and fully user-controlled.

Key features

Global rules: Apply CSS/JS to all websites (typography tweaks, accessibility improvements, debugging overlays). Per-website rules: Domain-isolated rule sets with independent enable/disable controls. SPA navigation support: CSS automatically re-applies on route changes; JavaScript re-run can be enabled in Settings. Optional live preview: Live JavaScript preview while typing in the popup editor (can be disabled in Settings). Backup & Restore: Export/import your full configuration safely with a local JSON backup. Flexible feedback: Desktop notifications, inline feedback, or silent mode. Multi-language interface: English, Spanish, German, French, Italian, Dutch, Polish, Portuguese, Turkish, and Russian.

Common use cases

Create custom dark mode rules for sites that don’t support it. Hide intrusive UI elements (banners, promos, sticky bars) with a few selectors. Automate repetitive tasks with small JavaScript snippets. Normalize fonts, spacing, and layout for a consistent browsing experience.

Privacy & safety

No tracking: Style Engine does not collect browsing data or analytics. Local-only: Your rules are stored locally in your browser. User-controlled: The extension runs only the code you explicitly write and save. No remote code: No external scripts are downloaded or executed.

Links

Website: https://glitchid.com/products/style-engine/ Documentation: https://glitchid.com/products/style-engine/documentation/ Privacy: https://glitchid.com/privacy/style-engine-privacy/ Terms: https://glitchid.com/terms/style-engine-terms/ Support: support@glitchid.com

Publisher: Glitchid

User Growth & Download Statistics

Manifest V3 Add-on
By:
Glitchid
Daily users:
1
Version:
1.2.0 Last updated: 2026-03-04
Version code:
6166022
Creation date:
2026-03-01
Risk:
Moderate risk impact High risk likelihood
Permissions:
Content scripts matches:
  • <all_urls>
Size:
102.28KB
Email:
su*****@glitchid.com
URLs:
Website ,Privacy policy
Full description:
See detailed description
Source:
Firefox Add-ons Store
Data ingested on:
2026-06-05
Compare stats and ranking:

Ranking

# 94,714 ▼ 3,376
Other rankings
#44 in javascript keyword 45 ▼ 1#250 in engine keyword 17 ▲

For Developers

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Contact the developer

Chrome-Stats does not own this Firefox add-on. Please use these information below to contact the Firefox add-on developer.
Developed by:
Glitchid
Firefox Add-ons Store
https://addons.mozilla.org/firefox/addon/style-engine/
Email:
su*****@glitchid.com
Website:
https://glitchid.com/products/style-engine/

Is Style Engine – Custom CSS & JavaScript Safe?

Risk impact
Risk impact measures the level of extra permissions an extension has access to. A low risk impact extension cannot do much harms, whereas a high risk impact extension can do a lot of damage like stealing your password, bypassing your security settings, and accessing your personal data. High risk impact extensions are not necessarily malicious. However, if they do turn malicious, they can be very harmful.

Style Engine – Custom CSS & JavaScript requires a few sensitive permissions. Exercise caution before installing.

Risk impact analysis details
  • Critical Allows access to all websites, posing a significant security risk as it can monitor and modify data from any visited site.
  • High ******* ******* **** *** ****** ***** *** ***** ** ******* **** ********* ********* ** * *********** *****
  • Medium ******* ******* ************* ***** *** ** ******* *** **** ******* ****** ******** *******
Risk likelihood
Risk likelihood measures the probability that a Firefox add-on may turn malicious. This is determined by the publisher and the Firefox add-on reputation on Firefox Add-ons Store, the amount of time the Firefox add-on has been around, and other signals about the Firefox add-on. Our algorithms are not perfect, and are subject to change as we discover new ways to detect malicious extensions. We recommend that you always exercise caution when installing a Firefox add-on.

Style Engine – Custom CSS & JavaScript may not be trust-worthy. Avoid installing if possible unless you really trust this publisher.

Risk likelihood analysis details
  • High This extension has low user count. Unpopular extensions may not be stable or safe.
  • Medium **** ********* *** ***** ** *** **** * ******* *** ********** *** *** ** ****** ** *****
  • Low **** ********* *** ******* **** **** * ****** **** ***** ******** *** **** ****** ** ** ****** *** *****
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