This example demonstrates SVG masking by layering a grid of horizontal and vertical rectangles over a circular cutout. The rectangles are created dynamically using the DOM API `document.createElementNS` with the SVG namespace. Two complementary masks, `circle-mask` and `circle-mask-2`, alternate between white and black fills to control visibility, producing a striped pattern inside the circle while keeping the surrounding area solid. The code relies on raw SVG manipulation rather than a visualization library, with only the `d3-selection` API imported but not actively used.