How did Valve do the candles in Harvest?

Stormcaller3801

L5: Dapper Member
Jul 5, 2009
249
28
I know that the candles themselves are props- I've got those. But I noticed that in the game they're lit. As we've yet to see vmf's for the event maps, I can't check those and I haven't seen any new sprites or props that would be the candle flames, though I might be missing those.

So how'd they do that?