Are sizing guidelines for office knitwear the same as for casual? Does it depend on the material? I know work sweaters will tend to be lighter for one thing. I have an H&M cardigan which is a size medium here below, but I'm wondering if to size up to a large. It's interesting, I'm ok wearing slim shirts, but in some areas like shorts and sweaters, I'm only starting to get the slimmer cuts so sometimes I might think something is snug but tha'ts only because it's outside my comfort zone. For example I've always imagined that the length of mens tops should always go over way over the backside. But how is this sweater size, and do I need to go up? Will it stretch?