/**
 * One theme watcher shared by every mounted card.
 *
 * A card's aura and progress ring are mixed from a colour read off its icon
 * (`--tx-stat-card-icon-color`, written as a resolved `rgb()` literal), so
 * a theme switch that re-points `--tx-color-success` and friends would leave
 * them on the previous theme's hue. A dashboard mounts four or five cards at
 * once; they subscribe here instead of each attaching a MutationObserver and
 * media-query listeners of its own. The observer and the listeners exist only
 * while at least one card is mounted.
 */
type ThemeListener = () => void;
/**
 * Calls `listener` on the frame after the page theme changes: a `class`,
 * `data-theme` or `data-tx-contrast` write on `<html>`, or the OS colour scheme
 * or contrast preference flipping. Returns the unsubscribe. Without a DOM (SSR)
 * it subscribes nothing.
 */
export declare function onThemeChange(listener: ThemeListener): () => void;
export {};