import { ElementRef, Renderer2 } from '@angular/core';
import { LyTheme } from '../../theme.service';
export declare class LyBg {
    private theme;
    private renderer;
    private elementRef;
    /** Default bg */
    private _bg;
    private _lastClass;
    private prefix;
    constructor(theme: LyTheme, renderer: Renderer2, elementRef: ElementRef);
    bg: string;
    css(bg: string): string;
}