Prompt:
Build "Kaisekitei", a standalone HTML page for slot 098 zen-sand-garden: raked sand canvas; drag to draw ripples around stones. The whole viewport is a single dry garden bed set inside a dark wooden frame (#3b2f25) with a small inset, rounded corners and a deep drop shadow. Palette: pale sand #d8ccb4 with a procedurally generated grain tile (light and dark single-pixel specks) used as a canvas pattern; grooves drawn as a dark umber line offset up-left and a warm white line offset down-right so every rake mark reads as embossed; charcoal stones with a radial gradient from warm grey to near black, a soft cast shadow and a speckled moss collar in olive greens; a vermilion seal (#a8402f) and drifting red petals as the only accents. Typography: vertical Mincho / Georgia heading "枯山水" with a small square seal, a Georgia paragraph of instructions with a tracked uppercase system-ui label "Kaisekitei · Dry Garden", italic Georgia for transient toasts, system-ui for controls. Layout: title block top-left; frosted-glass pill toolbar bottom-right with tine count toggles (Three, Five, Eight), a Smooth button and a Re-rake button; a centred italic toast near the bottom. Canvas engine: an offscreen sand canvas holds all raking; on load it is filled with the grain pattern, raked with horizontal parallel grooves every 9px, then each of five stones (positioned in normalised coordinates) gets six concentric elliptical ring grooves after the sand under the ring zone is smoothed. Stones are pre-rendered to sprite canvases at devicePixelRatio. Dragging: each pointer move of at least 4px first smooths a butt-capped strip the width of the rake with the grain pattern, then draws one groove segment per tine, using a normal vector blended with the previous one so curves stay continuous; tine points that fall inside a stone break the line. Tapping a stone smooths its surroundings and rakes fresh rings, with an expanding pale ripple ring as feedback and a toast. A dashed cursor circle previews the rake width; cursor switches to pointer over stones. Five petals drift diagonally across the garden. Resize copies the old sand into the new size (debounced). Reduced motion: petals stop and the canvas only redraws when something changes; toast transitions are removed.

Title: Kaisekitei Dry Garden

Description: A full-screen raked sand garden framed in dark wood. Fine, grainy sand is combed into straight parallel lines that swirl into concentric rings around five mossy stones. Dragging the pointer pulls a multi-tine rake through the sand, carving embossed grooves that follow the path smoothly, and tapping a stone resettles the sand around it in rings. Small italic phrases surface and fade as the viewer works, and a few red petals drift across the bed, making the page feel calm, tactile and unhurried.

Visual techniques:
- Offscreen canvas as a persistent drawing surface composited each frame
- Procedural grain tile used through createPattern for both base fill and smoothing
- Embossed grooves from paired offset strokes (shadow and highlight)
- Normal-vector tine offsets with smoothed normals for continuous multi-line raking
- Pre-rendered stone sprites with irregular quadratic-curve outlines, radial shading, shadowBlur and moss speckles
- Elliptical concentric ring generation and expanding feedback ripple
- Frosted backdrop-filter toolbar and vertical writing-mode title
- devicePixelRatio scaling, debounced resize that preserves the drawing, dirty-flag rendering under reduced motion

Interaction model: Drag anywhere on the sand to rake it; the number of tines is chosen from the toolbar. Tapping a stone rakes fresh rings around it with a soft ripple. Smooth wipes the bed to plain sand for free drawing, and Re-rake restores the classic lines and rings. Short contemplative messages appear after longer strokes and actions.