Personal website night mode

I added this Easter egg to my website a couple of versions ago, but I never got to sharing it. It's pretty old now, so I guess I can spoil it.

It's not much more than an Easter egg right now, as state isn't maintained when you navigate to another page (it's a static website hosted on GitHub pages).

I'm planning to introduce a much more useful implementation in the next update of my personal website. State will be maintained throughout the whole session and modes will probably change based on the time of day in your timezone.