Company Christmas Party

The company my husband works for is having a Christmas party on Sunday. He works for a company that lays pipe underground so it is a “blue collar” job and company. It’s going to be “casual” but it is obviously work related so I don’t want to go too casual and I want to look nice and represent my husband well. I’ve never done this so I have no idea what to wear! Any suggestions? I want to be cute and look pretty but also look nice and put together without being overdressed. Thanks in advance.