This example demonstrates how SVG masks can selectively reveal or hide overlapping grid lines. It renders horizontal and vertical stripes as SVG `rect` elements, each assigned a mask containing a black background and a white circle to create a transparent window. A second mask with inverted colors overlays the vertical stripes, producing a crosshatched pattern visible only within the circular region. The visualization is built using the raw `document.createElementNS` API to construct SVG elements dynamically in a loop, with the window size set to the full browser viewport.