Frontend Responsive Design Standards Rule: Mobile-first development with consistent breakpoints, fluid layouts, relative units, and touch-friendly targets. When to use this skill - When creating or modifying layouts that need to work on mobile, tablet, and desktop - When implementing mobile-first design patterns starting with mobile layout - When writing media queries or breakpoint-specific styles - When using flexible units (rem, em, %) instead of fixed pixels for scalability - When implementing fluid layouts with percentage-based widths or flexbox/grid - When ensuring touch targets meet min…