Responsive and Mobile Design

A candidate who says "I design mobile-first" without being able to explain what that actually changes about the design and build order hasn't said anything — it's become a resume buzzword said by people who still hand off a desktop mockup and shrink it. The interview-relevant version of this subject isn't the vocabulary (responsive, adaptive, mobile-first are not synonyms), it's the specific, checkable decisions those words imply: which unit a grid uses, how many points a touch target needs to be, why a gesture-only delete action fails a first-time user, and why a form that fits comfortably on a desktop screen has to become an entirely different flow on a phone.

This subject is #11 of 17 in the UI/UX Design Interview track. It assumes the process vocabulary from ux-vs-ui-and-the-design-process and leans directly on two named laws from interaction-design-principles — Fitts's Law (touch target sizing) and Hick's Law (progressive disclosure) — without re-deriving them. It also sets up case-study-design-a-mobile-app-from-scratch, where these constraints stop being abstract and become the thing you're actually trading off against a deadline. Where a visual-system decision from visual-design-fundamentals (type scale, spacing system) has a mobile-specific wrinkle, it's called out here rather than left implicit.

Interviewers use this material two ways: a direct knowledge check ("what's the minimum touch target size on iOS?") that filters out candidates who've never actually shipped a mobile screen, and a scenario check ("how would you redesign this desktop form for mobile?") that tests whether you reach for progressive disclosure and platform convention automatically or have to be walked to them.