Deception Step
This stairwell design is just cruel and unusal. Lines like this are usually used to mark the edge of an individual step, so why would the designer place one on the flat floor where there is no edge? This is just asking for the clumsiest of us to fall flat on our faces every time we think there’s a step that there isn’t.
Whoever designed this better have had a great reason for doing so, otherwise they’re about to be responsible for a whole slew of stairwell-related injuries.