Windows 10 reached EOS (end of support) on October 14, 2025. If you are on Windows 10, see this article.

Avatar for Username

搜尋 Mozilla 技術支援網站

防止技術支援詐騙。我們絕對不會要求您撥打電話或發送簡訊，或是提供個人資訊。請用「回報濫用」功能回報可疑的行為。

了解更多

此討論串已被封存。 如果您有需要幫助，請新增一個新問題

Firefox built-in PDF viewer stuck in light mode when privacy.resistFingerprinting is enabled

  • 1 回覆
  • 0 有這個問題
  • 234 次檢視
  • 最近回覆由 Paul
  • 封存

Xinyue Wang
Xinyue Wang

Hi everyone,

After enabling `privacy.resistFingerprinting = true` in `about:config`, I noticed that Firefox’s built-in PDF viewer (`pdf.js`) is always displayed in **light mode**, even though my system and browser themes are both dark.

I understand that RFP forces `prefers-color-scheme: light` to prevent fingerprinting, but this also affects internal components like the PDF reader. Unfortunately, the PDF viewer doesn’t provide a manual dark mode toggle.

Is there any **official or safe workaround** that allows keeping RFP enabled while still having the PDF viewer use dark colors?

Thanks!

Hi everyone, After enabling `privacy.resistFingerprinting = true` in `about:config`, I noticed that Firefox’s built-in PDF viewer (`pdf.js`) is always displayed in **light mode**, even though my system and browser themes are both dark. I understand that RFP forces `prefers-color-scheme: light` to prevent fingerprinting, but this also affects internal components like the PDF reader. Unfortunately, the PDF viewer doesn’t provide a manual dark mode toggle. Is there any **official or safe workaround** that allows keeping RFP enabled while still having the PDF viewer use dark colors? Thanks!

所有回覆 (1)

Paul
Paul
  • Moderator
  • Top 10 Contributor

Hi

The fingerprinting resistance is based on presets to try to achieve that aim and may not always lead to a configuration you would prefer for browsing.

An overview of a number of the settings are at https://support.mozilla.org/en-US/kb/resist-fingerprinting and I would avoid about:config if possible.