export type InjectStyle = string | InjectInlineStyle | InjectLinkStyle;
export type InjectInlineStyle = {
    type: 'style' | 'inline';
    content: string;
    media?: string;
};
export type InjectLinkStyle = {
    type: 'link' | 'external';
    href: string;
    media?: string;
};
export declare function injectStyles(el: HTMLElement | ShadowRoot, styles?: InjectStyle[]): Promise<void>;