TITLE: Ink Wash Mountains — a Chinese scroll that paints itself as you unroll it

PROMPT: Build a single self-contained HTML artwork that reads as a mounted Chinese ink-wash scroll. Palette: rice paper #f7f4ec, ink #1c1c1c, wash grey #6b7280, seal red #9c2b1f, mist #d8d2c4, on a mat of #efe9dc. Layout: a fixed painting panel inset by clamp(9px,2.2vw,38px) with a hairline ink rule and a deep soft shadow, over a 210vh scroll spacer; a vertical title 山水清音 at the right edge in writing-mode vertical-rl (Georgia with Songti SC / Noto Serif CJK SC fallback, .3em tracking, clamp(24px,3.4vw,46px)), a smaller vertical ui-monospace subtitle beside it, a red seal button lower-left (墨 in system-ui 700, rotated -2.4deg, inset hairline, red glow) and a ui-monospace caption along the bottom. Scene: paper fibre texture from two repeating gradients plus two mist radials; six mountain layers whose silhouettes are seeded random-walk ridge polygons (an LCG PRNG drives base/amp/bump sine humps plus a damped drift walk, clamped to 2-97%), stacked from rgba(107,114,128,.13) blur 7px at the back to rgba(28,28,28,.60) blur 0.8px in front, each with a horizontal ink-density gradient so the wet-ink edges read as brushed; a paper-coloured river band from 46% with mask-faded ripple lines; three blurred mist bands (linear-gradient #d8d2c4 with 17px blur) drifting on 34s/47s/61s alternate keyframes and parallaxing with the pointer. The scroll unrolls: a rolled-paper band and a wooden roller dowel sit at 58% height and translate down by progress·42% of the panel while the deep foreground band clip-path opens from inset(0 0 100% 0) to inset(0 0 0 0), revealing a dark foreground ridge and a vertical couplet 山色空蒙 / 水光潋滟. A lone boat (inline SVG hull, sail, mast, seated figure, blurred reflection) bobs on the river with a 7.5s float; hovering or focusing it slides a haiku card out of a clip-path. Six ink dots bleed outward (scale 2.5, blur 2.6px) on hover. Clicking the seal re-inks the scene: a fresh seeded ridge set is built into the hidden group, then the two groups cross-wipe through a 1.05s clip-path transition with the new group above, plus a stamp animation on the seal. Mountain entrance uses transform translateY(26px) plus blur, staggered 95ms, never opacity. Respect prefers-reduced-motion by disabling drift, bob, stamp and transitions. One inline <style>, one inline IIFE <script> at the end of body, no canvas, zero external references.

DESCRIPTION: A scroll painting that behaves like one: misty mountain silhouettes generated by a seeded random walk sit behind a river of pure negative space, with a single boat adrift and a red seal in the corner. The lower third is still rolled up at first; scrolling pulls the wooden roller down and the foreground ridge and its vertical couplet unroll into view. Clicking the seal re-inks the whole landscape with a new set of ridges while the old ink wipes away.

TECHNIQUES: Seeded LCG random-walk ridge polygons for hand-inked silhouettes; multi-layer blurred clip-path mountains for wet-ink edges; scroll-driven clip-path unroll of the foreground band; transform-driven roller and rolled-paper band; vertical writing-mode title and couplet; CSS-keyframe mist drift with pointer parallax on a lerped rAF loop; inline SVG boat with a rippling reflection; clip-path haiku reveal; two-group clip-path cross-wipe for the re-ink; transform-plus-blur entrance with staggered delays so a frozen render still shows the full page.

INTERACTION: Scroll to unroll the scroll: the wooden roller descends, the rolled paper slides away and the deep foreground ridge with its vertical couplet is revealed by an expanding clip-path while the mountains parallax gently. Move the pointer to push the three mist bands at different depths. Hover or keyboard-focus the boat to slide out a three-line haiku. Hover the six ink dots to watch them bleed and blur outward. Click the seal (or focus it and press Enter) to re-ink the landscape: new seeded silhouettes are generated and the old ink wipes away behind a clip-path crossfade, with a stamp animation on the seal.