This is a quick check to see if your browser (or child) has visited any concerning websites (or you forgot to clear your history!).

It doesn't use the :visited selector to tell anybody else, although that has been posted on HN before: https://news.ycombinator.com/item?id=7940766 https://news.ycombinator.com/item?id=7868211 https://news.ycombinator.com/item?id=30569396