This example demonstrates a drag-and-drop interface for organizing items into nested containers. Users can select and move draggable cards between an available items pool, collection containers, and target containers, with support for multi-selection, cloning, and collapsible sub-containers. The interface is built with custom HTML elements and the Drag and Drop API, using `dragstart`, `dragover`, and `drop` events to manage item movement. SVG graphics render simple shapes within some draggable items, while JavaScript handles selection state, group permissions, and data saving/restoring via button controls.