How does the layout change on a phone?

On a narrow screen the sidebar becomes a top bar plus a fixed bottom tab bar, with a More button that opens a slide-up sheet mirroring the sidebar. Trailwise and Settings are not in that sheet: they are icon buttons in the top bar at every width, along with the bell and your account menu. Panels stack into a single column, and activity rows reflow into labelled stat chips so every metric stays visible without sideways scrolling. Between those two widths the sidebar slides in from the side; only one navigation ever renders at a time. On a wide screen the sidebar collapses from its own corner toggle and remembers that you collapsed it.