/**
 * The stylesheet arm of an embedded surface's viewport-height normalization.
 * An auto-sized iframe has no independent block viewport: `100vh` resolves to
 * whatever height the HOST set from the last content measurement, so a
 * viewport-tall block plus any content after it grows the frame on every
 * measure (browser-observed: dashboards ratcheting to the 8192px cap, leaving
 * a tall run of empty background in the embed). Growing block sizes go
 * content-sized; everything else — including bounding `max-*` constraints —
 * stays untouched.
 */
/** Rewrite viewport-relative block constraints in a stylesheet's text to
 *  their content-sized forms (`height: auto`, `min-height: 0`). Idempotent:
 *  a sheet without viewport block sizes comes back unchanged (identity). */
export declare function normalizeViewportBlockCss(css: string): string;