After I installed version 134.0 of Firefox on my Debian sid system, web pages were rendered about 20% larger than they should be. The UI wasn't oddly scaled though; the issue was limited to the web page rendering area.
I tried working with layout.css.devPixelsPerPx, which comes up often in search engine results. But this scaled everything, including the UI.
Then I tried the first solution described in Fix UI Scaling and Large Fonts Issues in Firefox 103 and Later Versions, and it's working beautifully. Specifically, here's what I did (quoting from the article):
- Open Firefox and type about:config in the address bar and press Enter. It’ll show you a warning message, click on “Accept the Risk and Continue” button. It’ll open Firefox’s hidden secret advanced configuration page i.e. about:config page.
- Now create a new preference ui.textScaleFactor as NUMBER and set its value to 100 to fix the scaling and fonts issue.
This appears similar to the "--force-device-scale-factor" hack that I need to use to get Google Chrome to behave.