What is the opposite of "parallel" in architecture?

The two towers of the Verrazano Bridge are not parallel: they are slightly [???] to account for the curvature of the earth.

What is that word?

I believe it's as simple as "nonparallel". A synonym for this is "oblique" ("slanting or inclined in direction or course or position--neither parallel nor perpendicular nor right-angled"). https://www.vocabulary.com/dictionary/nonparallel

The opposite of parallel is right, orthogonal, normal or perpendicular. But these towers are not the opposite of parallel, they're simply not parallel. So you could just say "not parallel". You could also say "at an angle to each other". Technically, parallel lines are at angle of 0, and 0 is a number, but people will know what you mean. You could also say they "diverge" or "are divergent". Here, it would be implicit that they diverge as one goes up.