Nostalgia is a feeling and in this context, retro is a style. In the sense that they both refer to the past, maybe. Here to be nostalgic is to opine in the pres

Nostalgia is a feeling and in this context, retro is a style. In the sense that they both refer to the past, maybe. Here to be nostalgic is to opine in the present about the retro style. However generally speaking, one could have a feeling of nostalgia towards a smell, feeling, colour, moment etc, nostalgia does not have to be retro(style), unless retro is specifically retroactive, and that isn't the case here.