What problem does it solve? Designing native-feeling mobile apps requires knowing platform-specific conventions (iOS HIG vs Android Material 3), touch-target ergonomics, and thumb-zone reachability rules that generic responsive web design guidance does not cover. ## Core Features & Use Cases - Platform-difference matrix: Compares navigation, typography, components, gestures, and dialogs between iOS HIG and Android Material 3, with React Native cross-platform notes. - Touch-target ergonomics: Codifies the 44pt/48dp minimum sizes, hitSlop patterns, 8dp spacing rules, and thumb-zone placement with a common-mistake catalogue. - Per-industry design languages: Provides design signatures for fitness, finance, social, productivity, health, crypto, travel, education, and e-commerce apps, plus the Peak-End emotional design workflow. - Use Case: When asked to design a fitness app screen in React Native, apply the five-step process (context, structure, visual design, Peak-End emotion, polish) and verify every tap target meets the 44×44pt minimum. ## Quick Start Ask the AI to design a mobile app screen for a finance app following iOS HIG and Android Material 3 conventions with proper touch targets.