Can I keep (and use) a toaster oven on top of a small refrigerator?

I live in a small apartment and have a small fridge; it's maybe three feet tall.

I also have a toaster oven (max temp 230 C) that I'd like to keep on top of the fridge to save space.

Is this a bad idea?

Will heat from the toaster oven enter into the fridge? Will it stress the fridge? Are there problems associated with this set-up?