Responsive Storefront Overview Apply mobile-first responsive design patterns to a commerce storefront so that the shopping experience is fast and usable on phones, where the majority of commerce traffic originates. Key patterns include thumb-zone aware layouts, a sticky buy bar that appears on scroll, tap-target sizing, and responsive product grids that reflow without horizontal scrolling. When to Use This Skill - When more than 50% of storefront traffic comes from mobile devices (check your analytics) - When building a new storefront from scratch and laying out the CSS architecture - When au…