The colosseum says it gives +1 happy per 20% of per turn culture for the city. I see it giving +1 happy per 20% culture adjustment percentage. That would mean the most you could ever get is +6 happy. I have a city with several wonders that has 60 culture per turn. I think the rules say that should result in +13 happy. With the code as it is, my 60 culture/turn city gets +1 happy from a coloseum, and so does a city with 0 culture/turn. That doesn't seem like it could possibly be the intent.