/** @internal */
export interface ParseCssLengthUnitOptions {
    /**
     * The css unit to convert to a numeric value.
     */
    value: number | string;
    /**
     * @defaultValue `16`
     */
    fallbackFontSize?: number;
    /**
     * @defaultValue `document.documentElement`
     */
    container?: Element | null;
}
/**
 * This is used to convert CSS length units into a number. At this time, it really only supports
 * - `px`
 * - `rem`
 * - `em` (if {@link ParseCssLengthUnitOptions.container} is provided)
 *
 * @example Simple Example
 * ```ts
 * parseCssLengthUnit({ value: "24px" }) // 24
 * parseCssLengthUnit({ value: "3.5rem" }) // 56
 * parseCssLengthUnit({
 *   value: "3em",
 *   container: document.querySelector(SOME_QUERY),
 * }); // container's computed fontSize * 3
 * ```
 *
 * @see {@link https://developer.mozilla.org/en-US/docs/Learn/CSS/Building_blocks/Values_and_units#lengths}
 * @internal
 * @since 6.0.0 This was renamed from `unitToNumber`
 */
export declare function parseCssLengthUnit(options: ParseCssLengthUnitOptions): number;
