This may be a silly question, but we received a lot of really cute onesies as gifts, and I'm not sure how they're meant to be worn. In colder weather I've been using them as undershirts under her sleepers, but now it's starting to get warmer. Do you buy separate pants to go with them, or do they just wear them barelegged? And if it's the latter, do you put socks on them? We live in Wisconsin so it's only 60 degrees here and may not get hot for awhile.