Solarpunk

I would expect it to look a lot like fashion of the early 20th century for the working class. Clothes would naturally be baggier with greater ability to alter the clothing at certain locations to fit people wearing the clothes. The clothes would likely be made to be more durable on the understanding that undershirts and longer underwear would be worn underneath.

Since clothes would be owned and worn longer, fashion wouldn't shift as much. You would also see more second hand stores as it was common for the rich to sell or give clothes away to staff once it dropped out of fashion.