No, you can't. You can uses CSS as part of a keylogger in conjunction with Javascript that triggers your selectors based on keypresses. There are sites that a

No, you can't. You can uses CSS as part of a keylogger in conjunction with Javascript that triggers your selectors based on keypresses. There are sites that already ship javascript that change attributes that trigger selectors on certain keypress events. So by adding 'pure css' to these sites one would be able to log keystrokes on certain fields. One example is Instagram. It ships Javascript that changes suitable attributes of the password field on every keystroke. So adding the right CSS to Instagram could result in passwords being logged.