Description Two-column layout on desktop (map+list on the left, forecast on the right); on mobile, collapse to a map-then-forecast flow switched by a bottom tab bar, with the current step kept in sessionStorage. Rationale Responsive design is a functional requirement, explicitly including both portrait and landscape on mobile. sessionStorage (not localStorage) is the right fit here since which step you're on only needs to survive a reload within the tab, not a browser restart; this is also what satisfies the "use both Web Storage APIs" technical requirement, alongside the localStorage usage.