Mobile UX is not desktop UX scaled down. Small screens change what is visible, touch changes how accurately people can act, and variable connectivity changes how long every interruption feels. A strong mobile interface therefore makes priorities explicit instead of hiding complexity behind smaller components.
Design the task before the screen
Start with the main user goal and the information required to complete it. Secondary navigation, promotional modules and optional fields should not compete with that task. A narrow viewport is useful discipline: it exposes unclear hierarchy and unnecessary steps quickly.
Make touch interaction forgiving
Controls need enough size and spacing to avoid accidental activation, visible focus and state changes, and labels that remain clear without hover. WCAG 2.2’s minimum target-size criterion uses a 24 by 24 CSS pixel test with defined exceptions; the enhanced criterion recommends larger targets for easier operation. These are accessibility requirements and design inputs, not substitutes for testing the actual flow on real devices.
Build forms for mobile input
- Ask only for information needed at that stage of the task.
- Use appropriate input types, autocomplete tokens and clear error messages.
- Preserve entered values after validation failures.
- Keep the primary action visible and distinguish it from destructive alternatives.
Performance is interaction design
Loading delays, late layout shifts and blocked taps are experienced as interface failures. Reserve space for images, embeds and advertising; keep third-party code within a budget; and measure important journeys under realistic mobile conditions. Use the Mobile Web Performance Reality Check 2026 as the evidence-oriented starting point.
Design for interruption and recovery
Mobile sessions are frequently interrupted. Preserve progress, make state visible, provide useful back behaviour and avoid flows that depend on remembering information from a previous screen. For installed or offline-capable products, explain stale or unavailable data rather than silently failing.
Archive material in this cluster
For the normative accessibility detail, see W3C’s explanation of WCAG 2.2 Target Size (Minimum).