Invitation Wording to Define Attire for a Reception?

My work is hosting a cocktail reception at 7:30 pm in the evening to thank sponsors and volunteers of a major event we have annually. This is the first time we've had this "thank you" as a reception, and we want people to dress appropriately without calling it "business" or "business casual" because we don't want it to seem stuffy. It's fine to wear nice jeans with a blazer, etc. Any wording suggestions?

By Holly from Memphis, TN