Section 9 · Time, Motion & Interaction

Spatial Continuity and Z-Order

Definition

Z-order is the front-to-back stacking of elements. Spatial continuity is the consistent use of position, scale, and stacking across transitions so a user builds a stable mental model of where things are.

Why it matters

When screens simply replace one another, a user has no sense of place. Consistent spatial logic makes forward and backward navigation intelligible.

Example

A detail view that expands out of the element that opened it and collapses back into it, rather than appearing from nowhere.