Is Custom Css Rules Safe?

Custom Css Rules — Nerq Trust Score 50.5/100 (C- grade). Score based on 2 independent trust signals. Last analyzed: 2026-03-22

Custom Css Rules is a Firefox extension with a Nerq Trust Score of 50.5/100 (C-), based on 3 independent data dimensions. Last analyzed: 2026-03-22 Security: 90/100. Popularity: 15/100. Data sourced from addons.mozilla.org metadata, permissions analysis, and source code availability. Last updated: 2026-03-22. Machine-readable data (JSON).

Custom Css Rules Across Platforms

Same developer/company in other registries:

Safety Guide: Custom Css Rules

What is Custom Css Rules?

Custom Css Rules is a Firefox add-on — A Firefox extension to inject custom CSS into any website..

How to Verify Safety

Review permissions on addons.mozilla.org. Check if source code is available.

You can also check the trust score via API: GET /v1/preflight?target=Custom CSS rules

Key Safety Concerns for Firefox add-on

When evaluating any Firefox add-on, watch for: excessive permissions, data harvesting.

Measured Signals

Custom Css Rules has a Nerq Trust Score of 50/100 (C-). This score is a composite of automated measurements of security, maintenance, community, and quality signals.

Key Takeaways

• Custom Css Rules has a Trust Score of 50/100 (C-).
• The score is a measured composite — it is not a suitability judgment. Evaluate the individual signals against your own requirements.
• Query the current measured values via the Nerq API.

Disclaimer: Nerq trust scores are automated measurements based on publicly available signals. They are not endorsements, verdicts, or guarantees of suitability. Always evaluate the signals against your own requirements.