Cool. How long has the site been doing that? Does it only happen on Christmas? Have I just not noticed before now?

It's special bbcode I like to break out when I'm feeling festive.
It's either snow, or sometimes I animate spinning cogs.

That's brilliant! Love it. :)
How do the cogs look?

It was just the old cogs from the old site design. I don't think I'm hosting the gif file anywhere atm.
I'm not even sure where I've got it stored. Might be on my old hd.
Edit:

I figured I could make some new spinning cogs to match the new design.

edit: meh, a little long in the tooth. And the gif has a little stutter that the .swf doesn't have.
I should try the webp format instead.

edit2: Oh yeah animated webp is a lot nicer than gifs. More frames from smoother animation and a smaller filesize. The forum does support webp formats.Problem is, I can't host it anywhere, so I got to use a bloated gif.
Wait! I can host it on a github repository. Why have I never thought of this before?

If anyone is wondering, the BBCode is either:
[background=#ffffff]URL[/background] for just a banner at the top.
[bgall] and [backgroundfull] also work for a full page tiling background like I did with the snow.
#ffffff is the color code for white.

I literally had no idea.

I guess BBCode is just ancient forgotten sorcery.
Edit: I guess it's also easy to miss if the page is jumping directly to a post, you might not see the the top is animated.

It definitely looks super cool though! Love it. :)