This example demonstrates layered masking in SVG to create a grid of horizontal and vertical lines that intersect around a central circular opening. It uses D3’s `select` API alongside raw DOM manipulation to append two complementary masks, each defining a circular region of white or black fill. The code renders 100 horizontal and 100 vertical rectangles, applying one mask to each set so that lines are hidden or revealed in alternating patterns around the circle. The result is a moiré-like visual effect built purely from basic SVG shapes and mask definitions.