Portals

Summary

`createPortal` renders a component's children into a DOM node outside its parent hierarchy — the standard way to build modals, tooltips and dropdowns that need to escape overflow/z-index constraints.

• 1Build a modal component using `createPortal` into a `#modal-root` div.
• 2Notice that events still bubble through the React tree, not the DOM tree.
• 3Compare a portal-based modal to one nested normally to see the z-index/overflow issues it solves.