Laws of UX
Law of Common Region
Elements sharing a bounded area are perceived as grouped (Gestalt). Cards, sections, fieldsets — boundaries create relationships without needing proximity alone. Supports info & relationships (WCAG 1.3.1).
In plain terms
Drawing a box or shared background around items makes them feel like a group, even when they're spread apart.
Why this matters
A border or shared background instantly signals 'these go together', reducing the effort to parse a layout — valuable for users carrying high cognitive load or attention difficulties.