I worked in a subsidiary of Hallmark, Irresistible Ink. It was casual, except for those who had customer contact. If they didn't have contact that day, they could be casual too. Getting along was encouraged, I frequently sat down with the director for cups of coffee, figuratively at least. Celebrations were occasionally hosted by the company, and we often gathered offsite on our own.
We had a upper management person from corporate who visited occasionally, he told this story: He was on a conference call with a Hallmark VP in the room. The customer on the line said something stupid and someone in the room made a face. Later the VP "ripped this guy a new one" for doing that. So, you see, keeping a professional demeanor at all times is very highly valued.