Usage
Panel is one tile of a workspace: a bordered surface with a header and, when needed, a body. It imports no layout library, owns no position or size, and does not track windows. Whether a panel is popped out is the header's variant, which the host sets.
Panel — Root section; give it aria-label when it should be a region landmark.PanelHeader — Title or tabs, actions, pop-out, collapse, dock-back, fullscreen and the actions menu (last at the inline end unless actionable={false}).PanelBody — Named inline-size container (panel) for content queries.PanelError — role="alert" failure state that keeps the header reachable.children may be only a PanelHeader. The root hugs the header in an auto block-size parent and still fills a fixed-height tile. Popped-out window-frame padding applies only when a PanelBody is present.
Card or page chrome.Drawer.