![Rectangle, ellipse and triangle](https://i.stack.imgur.com/KfpL4.png)

Suppose we have a flat drawing with rectangle, ellipse and triangle (see picture).

What prepositions can we use in these cases:

1. The ellipse is […] the rectangle.
2. The triangle is […] the rectangle.

Suggestions: "under", "below", "beneath", "underneath"; "behind"; others.

I understand meaning of these prepositions in 3D world. But in generic case of appearance of 2D painting on screen (say, at web-site), when I don't have any guess about user's devices and their disposition (e.g. he may use CRT monitor with vertical screen, or put his tablet horizontally on table, or lay on his back with keeping screen horizontally) — what is the best word choice? Or every word would be equally ambiguous without context knowledge?

So, question is not about prepositions themselves, but about their traditional usage for specifying disposition of 2D objects on screen — and their potential ambiguity for user with unknown screen orientation.