This example reproduces a Sol LeWitt wall drawing using pure browser APIs, with no external libraries. It renders 100 horizontal and 100 vertical rectangles in SVG, layered so that a circular mask reveals the grid pattern at the center while masking the opposite orientation at the edges. The code constructs the SVG, masks, and shapes programmatically via `document.createElementNS`, setting attributes like `fill`, `r`, and `mask` on each element. The layout adapts to the full viewport size using `window.innerWidth` and `window.innerHeight`.