Obviously there is a bit of stripping to do around the edges still, and something is going on with that second stair. After the second coat of Citristrip didn't do half as much as the first coat, I decided to see if sanding would help. It definitely did. I started with 60 grit and will do a finish sand of 120 and 220 grit.
You can see there's a bit of color difference between the steps.
Ignore the third step; I sanded it because I hope that by at least scuffing up the polycrylic, it will be easier for the stripper to work. But it has not been stripped yet, so it's representative of nothing.
I hope to get this completely done during the kids' Christmas vacation. This was my one big December project and it's been slow going, mostly because stairs are, by definition, a high-traffic area and it's hard to find a good time to leave the stripper on for several hours. But I think now I can get a rhythm started.