App Shells
The frame around everything else: navigation rail, top bar and docks, in four arrangements.
The classic left-sidebar dashboard: a collapsible-icon nav rail with a tenant switcher and nav groups beside a floating inset surface carrying a metric row, a revenue trend and an overnight activity feed. Skip link, one main landmark, active-route indicator and command trigger included.
Two navigation levels plus a summoned third surface: a permanent 56px icon rail picks the area, a collapsible second panel lists that area's sections, and the floating inset carries the settings screen. A resizable right-hand SideDock holds the change history — a column above 1100px, an overlay below it. The icon rail is deliberately not a Sidebar, so it survives every breakpoint while the section panel becomes a sheet.
Three-zone mail shell: the collapsible icon rail, a searchable message list, and a reading pane sharing one floating inset surface. A variation on the dashboard shell, not a separate idea; below md the two content zones become a drill-down.