/**
 * Is a page `background` value an image source (URL / data URL / path) rather
 * than a color or gradient? Mirrors the canvas classification: anything
 * `colorToRGBA` can't parse and that isn't a gradient is treated as an image.
 * (The converters historically sniffed for substrings like '.jpg', which
 * missed webp/avif/data:/blob:/relative-path backgrounds.)
 */
export declare function isImageBackground(background: string): boolean;
/**
 * Render order for a page's children: `alwaysOnTop` elements render last
 * (on top), mirroring the canvas renderer.
 */
export declare function orderByAlwaysOnTop<T extends {
    alwaysOnTop?: boolean;
}>(children: T[]): T[];