import type { Root } from "postcss";
import postcss from "postcss";
/**
 * Checks if a CSS variable already exists in the stylesheet
 * @param root The PostCSS root to search in
 * @param selector The CSS selector to look for (e.g., ":root", ".dark")
 * @param variable The CSS variable to check for (e.g., "--background")
 * @returns Whether the variable exists
 */
export declare function cssVariableExists(root: Root, selector: string, variable: string): boolean;
/**
 * Safely adds CSS variables to a root without removing existing ones
 * @param root The PostCSS root to modify
 * @param selector The CSS selector (e.g., ":root", ".dark")
 * @param variables Map of variables to add
 */
export declare function addVariables(root: Root, selector: string, variables: Map<string, string>): void;
/**
 * Safely adds CSS variables inside an @layer or @at-rule block
 */
export declare function addVariablesToLayer(layer: postcss.AtRule, selector: string, variables: Map<string, string>): void;
/**
 * Safely merges @theme blocks without overwriting user values
 */
export declare function mergeTheme(root: Root, newThemeVars: Map<string, string>): void;
/**
 * Safely adds missing @variant definitions
 */
export declare function addVariants(root: Root, newVariants: Map<string, string>): void;
/**
 * Safely adds missing utilities to @layer utilities
 */
export declare function addUtilities(root: Root, newUtilities: postcss.Rule[]): void;
/**
 * Safely adds missing @custom-variant definitions (v4 syntax)
 */
export declare function addCustomVariants(root: Root, newCustomVariants: Map<string, string>): void;
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