First litter of mice today

My albnino finally gave birth today while I was at work, but I haven't seen her go in the nest with them yet. Is she supposed to be nursing them and keeping them warm, or is it normal for her to be out and about while they squirm around in the nest?

Females do not always stay in the nest as long as the babies are fed (look for milkbands on the babies) they will be ok.

Thanks Deborah, I'll keep an eye on them. I'm just glad to see she hasn't eaten any. I seperated her when I saw she was pregnant, and I've been feeding her a lot of homemade high protein/high fat food bars. The room they are in is about 76-77 degrees. Is that ok, or should I give them supplemental heating?

No your temps are good, I usually keep mine between 72-76 and they are healthy and VERY prolific.