/** Deduplicating CSS class builder. Mirrors CMStyle from OfficeImport. */
export declare class StyleBuilder {
    private counter;
    private cache;
    /** Register CSS declarations and get back the class name (e.g. "s5"). */
    addClass(css: string): string;
    /** Emit the <style> block content with triple-specificity selectors. */
    getStyleSheet(): string;
    /** Reset counter and cache (called per-slide). */
    reset(startIndex: number): void;
    get nextIndex(): number;
}