how lighting affects Fight!

there is a section dedicated to how lighting and terrain affect range and cover. However, the section in Fight! only talk about terrain, not mentioning obs for lighting. Does fighting at night, or moonless night, or firelit night impart specified obs, or do we just make them up on our own?

What obs would one suggest for fighting at night in firelight? I assume that it would affect orcs and elves less due to their special vision.

I think it’s listed somewhere else, just not specifically in Fight. I’d say +1 Ob as a general rule, though whatever the book says is correct.