Generally yes, if you stick just to CSS you can log HTTP request initiated by user's interaction or user's environment. To name some environmental: locally ins

Generally yes, if you stick just to CSS you can log HTTP request initiated by user's interaction or user's environment. To name some environmental: locally installed fonts, viewport dimensions, colour depth, resolution etc. Interaction is anything pointer position related, focus management, and to some degree you can do simple kind of "keylogging" or text character presence detection. https://github.com/jbtronics/CrookedStyleSheets https://github.com/jbtronics/CrookedStyleSheets https://news.ycombinator.com/item?id=16157773 https://news.ycombinator.com/item?id=16157773