# Custom CSS rules

> A Firefox extension to inject custom CSS into any website.

Canonical page: [https://chrome-stats.com/d/custom-css-rules](https://chrome-stats.com/d/custom-css-rules)

## Overview

- **ID:** `custom-css-rules`
- **Platform:** Firefox
- **Type:** Firefox add-on
- **Status:** Available
- **Publisher:** sina
- **Category:** web-development,appearance,tabs
- **Daily users:** 3
- **Version:** 1.1
- **Last updated:** 2025-04-04
- **First published:** 2025-04-01
- **Size:** 97 KB
- **Data as of:** 2026-09-04
- **Store listing:** [Firefox Add-ons Store](https://addons.mozilla.org/firefox/addon/custom-css-rules/)
- **Website:** [https://sinajalalvandi.ir](https://sinajalalvandi.ir/)

## Description

A simple Firefox browser extension that allows you to inject your own custom CSS rules into any website. Styles are saved per domain and applied automatically whenever you visit the site.

## Rankings

- #54,754 — Overall
- #55 — rule
- #177 — custom font
- #178 — custom feed
- #188 — customer

## Permissions and access

### Permissions

- `storage`
- `activeTab`
- `scripting`

### Host permissions

- `<all_urls>`

### Content script matches

- `<all_urls>`

## Safety

- **Risk impact:** Moderate risk impact
- **Risk likelihood:** Moderate risk likelihood

### Analysis details

- Allows access to all websites, posing a significant security risk as it can monitor and modify data from any visited site.
- This extension has low user count. Unpopular extensions may not be stable or safe.

> Some risk analysis details are omitted from this free response. [Upgrade to view the full analysis](https://chrome-stats.com/pricing).

## Similar extensions and apps

- [Your Custom Css](https://chrome-stats.com/d/your-custom-css) — 93 users
- [Per-Site CSS Injector](https://chrome-stats.com/d/per-site-css-injector) — 16 users, 5.00 / 5
- [CSS Edit](https://chrome-stats.com/d/css-edit) — 12 users
- [Custom CSS Injector](https://chrome-stats.com/d/custom-css-injector-iue) — 1 users
- [Simple Custom CSS](https://chrome-stats.com/d/simple-custom-css) — 5 users
- [CustomCSS Injector](https://chrome-stats.com/d/customcss-injector) — 818 users, 4.27 / 5
- [Per-Domain User CSS](https://chrome-stats.com/d/per-domain-user-css) — 19 users
- [CSSOverride](https://chrome-stats.com/d/cssoverrider) — 29 users
- [CSSOverride](https://chrome-stats.com/d/cssoverride) — 28 users
- [stylextension](https://chrome-stats.com/d/stylextension) — 3 users, 3.00 / 5
- [CSSOverride](https://chrome-stats.com/d/css-overrider) — 30 users
- [Custom Style](https://chrome-stats.com/d/custom-style) — 7 users, 4.33 / 5

---

Source: [Chrome-Stats](https://chrome-stats.com/d/custom-css-rules)