/**
 * Colour nudging detection — EDPB Guidelines 03/2022 § 3.3.3.
 *
 * A "positive" colour (green = go, approve) on the accept button combined with
 * a "negative" or neutral colour (grey, red) on the reject button steers users
 * toward consent without technically hiding the refusal option.
 */
/** Returns [hue 0–360, saturation 0–100, lightness 0–100]. */
export declare function rgbToHsl(r: number, g: number, b: number): [number, number, number];
export type ButtonHue = "green" | "red" | "grey" | "blue" | "neutral";
/**
 * Classify the perceptual "valence" of a colour:
 * - green  → positive, approval (h 80–165, s ≥ 25)
 * - red    → negative, danger   (h ≤ 20 or ≥ 340, s ≥ 25)
 * - grey   → neutral / muted    (s < 20)
 * - blue   → informational      (h 195–265, s ≥ 25)
 * - neutral → anything else
 *
 * Very dark (<10 L) or very light (>93 L) colours are treated as neutral
 * because their hue carries little visual weight in a button context.
 */
export declare function classifyHue(r: number, g: number, b: number): ButtonHue;
export interface ColourNudgingResult {
    acceptHue: ButtonHue | null;
    rejectHue: ButtonHue | null;
    /** True when accept is green and reject is grey or red. */
    isNudging: boolean;
}
/**
 * Detect colour nudging between the accept and reject buttons.
 *
 * Returns `isNudging: true` when the accept button has a "positive" hue (green)
 * while the reject button has a "negative" or neutral hue (grey or red).
 */
export declare function detectColourNudging(acceptBg: string | null | undefined, rejectBg: string | null | undefined): ColourNudgingResult;
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