[Xeanort]

False: it is possible with just CSS [1][2] to track screen resolution, browser engine, fonts, mouse movements and inputs.

[1] https://github.com/jbtronics/CrookedStyleSheets

[2] https://github.com/maxchehab/CSS-Keylogging

[shakna]

Both those methods rely on the browser not prefetching certain resources, which they are absolutely allowed to prefetch.

So if a browser changes the prefetching algo, the method is immediately broken. (For example enabling network.predictor.enable-prefetch in Firefox).

It isn't an inherent weakness of CSS itself.