This example reproduces a Sol LeWitt wall drawing using SVG masks to create a circular window into intersecting grids of vertical and horizontal bars. The code builds two complementary masks—one with a white background and black circle, the other inverted—so that vertical lines appear outside the circle while horizontal lines appear inside it. It uses raw DOM manipulation with `document.createElementNS` and D3’s `selection` import, and sizes the artwork responsively to the viewport dimensions.