Ask HN: Why is there a black bar at the top of the site?

It honors the passing of someone important. In this case, that person is Stephen Hawking.

Interestingly, the article about Hawking's death is now the most upvoted article ever on HN, beating Steve Jobs' obit by quite a wide margin:

Symbolic mourning of Stephen Hawking I believe.

I don't know why it's there, but it's breaking my HN client app on iOS :-/