/** Every element inside `root` a Tab press can reach, in DOM order. */
export declare const tabbableWithin: (root: ParentNode) => HTMLElement[];
/**
 * The element a keyboard user actually lands on for `root`: `root` itself when it is tabbable, else
 * its first tabbable descendant. `null` when the subtree holds nothing reachable — a decorative or
 * disabled control, which the caller has to decide about.
 */
export declare const firstTabbable: (root: HTMLElement) => HTMLElement | null;