/**
 * Helpers for the CSS-valued Elemental properties (`font_size`, `line_height`,
 * document `padding`).
 *
 * The backend validates these at save/render time and silently drops anything
 * that doesn't match — see `api/send/validation/schema/css-values.ts` in the
 * backend repo. The regexes here mirror that contract so the designer never
 * writes a value the renderer will throw away:
 *
 *   font_size    px only                        "18px"
 *   line_height  px or unitless multiplier      "24px" | "1.5"
 *   padding      1-4 space-separated lengths,   "8px 30px" | "0 30px"
 *                each a bare 0 or a px value
 *
 * Internally the designer stores font size / line height as plain px numbers,
 * because every editor control for them is a px number input. A unitless
 * `line_height` coming from an API-authored template is therefore resolved
 * against the effective font size on import (see `lineHeightToPx`).
 */
/** px only — matches the backend CSS_PX_REGEX. */
export declare const CSS_PX_REGEX: RegExp;
/** px length or unitless multiplier — matches the backend CSS_LINE_HEIGHT_REGEX. */
export declare const CSS_LINE_HEIGHT_REGEX: RegExp;
/** 1-4 space-separated lengths, each a bare `0` or a px value. */
export declare const CSS_PADDING_REGEX: RegExp;
/**
 * Parse an Elemental px value (e.g. "18px") into a number.
 * Returns undefined for anything the backend would reject.
 */
export declare const parsePxValue: (value?: string | null) => number | undefined;
/** Serialize a px number back to Elemental form. Drops non-positive/invalid input. */
export declare const formatPxValue: (value?: number | null) => string | undefined;
/**
 * Resolve an Elemental `line_height` to px.
 *
 * A unitless multiplier is only meaningful relative to a font size, so it is
 * multiplied by `effectiveFontSize` (the block's own `font_size` when set,
 * otherwise the tier preset). Keeps the editor's px control honest and
 * round-trips as px, which is also what the renderer prefers — Outlook
 * mishandles unitless line-heights.
 */
export declare const lineHeightToPx: (value: string | undefined | null, effectiveFontSize: number) => number | undefined;
export interface PaddingSides {
    top: number;
    right: number;
    bottom: number;
    left: number;
}
/**
 * Expand a CSS padding shorthand into its four sides, following the standard
 * 1/2/3/4-value rules. Returns undefined when the value isn't a shorthand the
 * backend accepts.
 */
export declare const parsePaddingShorthand: (value?: string | null) => PaddingSides | undefined;
/**
 * Collapse a padding shorthand to the vertical/horizontal pair the simplified
 * Frame control exposes. Asymmetric 3/4-value shorthands (authored via API or
 * the advanced view) fall back to their top/left sides for display.
 */
export declare const paddingShorthandToVH: (value?: string | null) => {
    vertical: number;
    horizontal: number;
} | undefined;
/** Build the `vertical horizontal` shorthand the Frame control writes. */
export declare const formatPaddingVH: (vertical: number, horizontal: number) => string;