//#region src/inject.d.ts
/**
 * Inject the pantoken stylesheet into `document.head` once. Returns the created element, if any.
 *
 * @example Inject on the default document
 * ```ts
 * import { inject } from "@pantoken/css/inject";
 *
 * const style = inject(); // <style data-pantoken> appended to document.head
 * ```
 *
 * @example Inject into a specific document (e.g. an iframe)
 * ```ts
 * import { inject } from "@pantoken/css/inject";
 *
 * const frame = document.querySelector("iframe")!;
 * inject(frame.contentDocument ?? undefined);
 * ```
 */
export declare function inject(doc?: Document | undefined): HTMLStyleElement | undefined;
//#endregion