/** One appearance axis value as a consumer may pass it: a rung name, a presence flag, or nothing. */
export type AppearanceValue = string | boolean | null | undefined;
/**
 * Resolves appearance axes to the `data-*` attributes the skin reads, so a
 * consumer may set either the prop (`size="lg"`) or the attribute
 * (`data-size="lg"`) and both render the same. The prop wins when both are
 * given; `false`, `null` and `undefined` leave the attribute off; `true`
 * writes a bare presence attribute.
 *
 * @param values - Axis name to prop value, e.g. `{ size, iconOnly }`; camelCase keys map to kebab-case attributes.
 * @param attrs - The pass-through attributes the consumer supplied, read for `data-<axis>` fallbacks.
 * @returns A `data-<axis>` record to spread after the pass-through attributes.
 */
export declare function appearanceAttrs(values: Record<string, AppearanceValue>, attrs?: Record<string, unknown>): Record<string, string | undefined>;