Dress Attire on Costa Ships

[pbparker]

I have never sailed with Costa before but I'm booked on a European cruise this summer. I would appreciate any advice about just how formal men and women dress on this line, in general. For instance, I consider Celebrity and Princess very formal on formal nights, but I consider Carnival, RCCL and Norwegian to be less so, even on their posted formal nights. Where do the Costa ships fit in? Many thanks.