This teaches Claude to build layouts that work across all screen sizes and input methods. You get concrete breakpoint recommendations (small at 375-639px up through XL at 1440px+), specific responsive patterns like column drop and off-canvas navigation, and guidance on adapting for touch versus mouse versus keyboard. The mobile-first and content-first approaches are both covered, plus practical details like 44px minimum touch targets and fluid typography scaling. Worth using when you need Claude to think through the full responsive spectrum instead of just throwing in a few media queries. The real device testing reminder and accessibility checkpoint advice are solid additions that often get skipped.
npx skills add https://github.com/owl-listener/designer-skills --skill responsive-design