This example recreates Sol LeWitt’s Wall Drawing Exercise 9, generating a grid of irregular polygons whose corners are randomly offset. The page fills the browser window with an SVG, drawing alternating black and white horizontal and vertical bands that are clipped to each polygonal region using SVG `<mask>` elements. The polygons split the viewport into a 3×3 grid, with each cell’s vertices jittered by random values. The code uses plain SVG APIs like `createElementNS`, `setAttribute`, and `appendChild`, with random offsets via `Math.random`.