The navigation column a dashboard is organised around — collapsed to a rail, or floating inside the page.
Full-height column that collapses to a 68px icon rail, with tooltips standing in for the labels it drops.
Sidebar as a floating card on a tinted page, with collapsible sections and a workspace switcher.
Two columns: a 64px rail of sections that never scrolls, and a panel showing one section at a time — the same press that switches sections opens the panel on a phone.
Driven by a menu array rather than markup: labelled sections and nested groups that expand in place when the column is wide and open as flyouts once it is a 68px rail.