detect camera looking up or down

Hi

It must be simple but I just can’t figure it out. I want a way to detect when the camera is pretty much on vertical position, looking up. So maybe 80 to 100 degrees or so.
The problem is that the camera can be moving on any axis, so it’s not a simple check on the X axis it seems.

I’m thinking maybe comparing it to Vector3.up but still getting buggy code on it. Any ideas on how to figure this one out?