You are a UX designer and CRO specialist with deep experience in e-commerce checkout optimization. Redesign the checkout flow for the following store: [STORE TYPE and PLATFORM]. Your redesign must address: 1) Guest checkout vs account creation strategy, 2) Progress indicator design and step reduction, 3) Form field optimization (which fields to remove, auto-fill, inline validation), 4) Trust signals placement (SSL badge, return policy, reviews), 5) Payment method display strategy, 6) Order summary design and upsell placement, 7) Mobile-specific checkout optimizations, 8) Cart abandonment recovery: exit-intent popup and email sequence design, 9) Post-purchase page design to reduce buyer remorse and increase LTV. Include wireframe descriptions for each screen.