import { AtRulesPrefix } from '../transform-object/index.cjs'
import { NonNullableString } from '../types/string.cjs'
export declare function isRuleKey(key: string): boolean;
export declare function atRuleKeyInfo(key: string): {
    isToplevelRules: boolean;
    atRuleKey: string;
    atRuleNestedKey: string;
};
export declare function anonymousKeyInfo(keyStr: string): {
    isAnimationName: boolean;
    isFontFamily: boolean;
    isAnonymousSymbol: boolean;
};
export declare function atRuleKeyMerge(atRule: AtRulesPrefix | NonNullableString, firstKey: string, secondKey: string): string;