The infamous "a:visited" tracking didn't simply track your visits from Google — it tracked all your visits across entire Internet. Browser vendors are bunch of lazy hacks, who can't even implement per-site link history (just like they failed to implement per-site cookies). All "a:visited" states are source from single SQLite database, that stores your full web history. THAT is the "CSS Tracking", because it can tell a page about visits from completely different domains. Instead of separating your web history per-domain those <censored> have crippled :visited selector in several undocumented ways.
But who asked them to? As far as I know, the spec says nothing about per-site histories, and I find it much more useful to know if I already visited a site, regardless of the origin - for example, if I'm researching a topic, two or more sites might link to the same place, and I don't want to open it multiple times.
Plus, the idea that one can look at a modern browser, which are some of the most complex software packages being developed, and think "clearly these people don't know how to add an 'origin' column to a SQLite database", well, it boggles the mind.
Fortunately, browser developers are some of the most competent people in the word. They would never give web pages too much power by letting them start CPU threads, use OpenGL, allocate arbitrary amount of memory or read your battery level to set exorbitant taxi tariffs for people in a pinch. Browsers are well-designed and highly secure, because they are being updated with security fixes every day, sometimes even multiple times a day.
To be fair there has been an ugly solution to this recently, the `__Host-` cookie prefix:
If you want to prevent this kind of spying, the solution is to load these kind of interactive background images either always or never, but not on the interaction they're supposed to track.