What problem does it solve? Interfaces often feel subtly off due to small compounding details like mismatched border radii, jarring animations, or misaligned icons. This Skill provides a systematic set of design engineering principles to identify and fix those polish issues in frontend code. ## Core Features & Use Cases - Design Principle Checklist: 19 concrete principles covering concentric border radius, optical alignment, shadow-based elevation, interruptible animations, tabular numbers, hit areas, and icon stroke weights. - Structured Review Modes: Quick mode for high-traffic paths (HIGH/MEDIUM findings, cap of 5) and full mode for comprehensive audits (cap of 15), with severity-rated findings tables showing before/after code. - Framework-Aware Guidance: Adapts fixes to the project's existing styling system (Tailwind, plain CSS, CSS-in-JS) and motion library (motion, framer-motion, or CSS-only fallbacks). - Use Case: When a button press feels unresponsive or a card layout looks off, run a review to get specific findings like adding active:scale-[0.96] or correcting nested border radii with exact file and line references. ## Quick Start Review my UI components for polish issues and suggest fixes following interface design principles.