This example reproduces a Sol LeWitt wall drawing using only the SVG API and JavaScript. The artwork shows a grid of horizontal and vertical bars whose visibility is masked by two overlapping triangles, one white and one black, creating a dynamic interplay of line and shape. The code creates an SVG canvas sized to the browser window, then uses `document.createElementNS` to construct 150 horizontal and 150 vertical rectangles. Two SVG masks (`polygon-mask` and `polygon-mask-2`) selectively reveal or hide these bars, with the first mask containing a white triangle on black, and the second a black triangle on white.