This is a quick check to see if your browser (or child) has visited any concerning websites (or you forgot to clear your history!).<p>It doesn't use the :visited selector to tell anybody else, although that has been posted on HN before:
<a href="https://news.ycombinator.com/item?id=7940766" rel="nofollow">https://news.ycombinator.com/item?id=7940766</a>
<a href="https://news.ycombinator.com/item?id=7868211" rel="nofollow">https://news.ycombinator.com/item?id=7868211</a>
<a href="https://news.ycombinator.com/item?id=30569396" rel="nofollow">https://news.ycombinator.com/item?id=30569396</a>