Re: [csswg-drafts] [css-env][css-values] UAs inconsistent in how OS font settings affect the default font-size `medium` (#10674)

I also have the same concerns about using the word 'zoom'. I'd be happy to support `preferred-text-scale-factor` as well.

> This information is already completely exposed, since it affects the layout of text on the page. With a little bit of scripting you can obtain the exact value without much trouble; this is just making that script-fiddling unnecessary, since it's a useful thing for the page to be able to respond to.
> 
> So, no new fingerprinting surface is exposed, it just makes existing surface slightly easier to read.

That's not my understanding. I'm not aware of any API on the web platform that exposes the OS text scale setting, except on Firefox for Android with the 'Automatic font sizing' setting enabled (see https://github.com/w3c/csswg-drafts/issues/10674#issuecomment-2605233153), where you could use `getBoundingClientRect` to get the actual height of a box affected by the scaled font. [I've made a CodePen to demo it.](https://codepen.io/joshtumath/pen/azbYOEz)

In my investigation of the major browsers, I couldn't find any other examples where OS font size or accessibility settings influenced the size of a font rendered on a web page. Therefore, I don't see how that fingerprinting surface is currently exposed.

Am I missing something? 😅 

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Received on Wednesday, 19 March 2025 00:50:34 UTC