I think dragn sneezed on her bamboo steamer, or so it looks.
Lol, but yes, you don't want the pan underneath to be smaller, not only because it could catch on fire, but also the steam will drip down the insides and onto your stove.
We also use our steamer a lot for things like shu mai, or dumplings.
I've put baby bok choy leaves down first, then the shu mai, then another tray of just whole baby bok choy.
After removing the cooked shu mai, I like to toss the bok choy with soy and butter.