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Modal components require stacking context, focus management, and real device testing
Source type Practitioner
Confidence Medium
Last verified 2026-03-25
Topics design-engineering

Insight: Modal component architecture requires three critical considerations: z-index management through stacking contexts (preventing child-level reordering), keyboard focus containment (tab trapping and focus restoration), and real device testing that reveals mobile viewport and OS-specific issues. Testing in browser responsive mode misses critical platform behaviors.

Detail: Z-index solutions: create new stacking contexts on modals to ensure children cannot bypass layering. Focus management: use focus-trap libraries rather than reimplementing; contain tab order and restore previous focus on close. Mobile testing: iOS scrolling and browser UI edge cases require actual devices; position:fixed and viewport height interact unexpectedly across platforms. Principle: design system strength depends on processes and testing as much as component code.

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