/**
 * Options for {@link addDarkModeSupport}.
 */
interface DarkModeOptions {
  /**
   * Extra CSS to wrap in a `@media (prefers-color-scheme: dark)` block (the dark-mode overrides).
   */
  styles?: string;
}
/**
 * Adds dark-mode hooks to an HTML email: the `color-scheme` / `supported-color-schemes` meta tags and,
 * when provided, a `@media (prefers-color-scheme: dark)` style block.
 *
 * Injected into `<head>` (created after `<html>` if absent, otherwise prepended).
 * @param html The HTML email.
 * @param options Dark-mode options. See {@link DarkModeOptions}.
 * @returns The HTML with dark-mode support added.
 */
declare const addDarkModeSupport: (html: string, options?: DarkModeOptions) => string;
export { DarkModeOptions, addDarkModeSupport };