Backdrop

Backdrop renders a scrim over the viewport — full dim for loading or modal blocking, or a spotlight cutout that highlights one element by anchor_id. Bind config.open; pass on_click to dismiss on scrim tap. Prefer composed scrims inside Dialog and Drawer unless you need a standalone loading overlay or spotlight highlight. Pair spotlight cutouts with SpotlightTip and SpotlightTour.

• Modal dialogs and drawers that need a dimmed page behind the surface
• Loading states that block interaction until work completes
• Any overlay that should signal a temporary state change

• Bind config.open to show or hide the scrim.
• Pass on_click when clicking the scrim should dismiss the overlay.
• Put a Spinner or other content in children for loading overlays.