This example demonstrates how SVG masks can combine two complementary cutout patterns. It renders a full-screen SVG canvas where a grid of vertical and horizontal rectangles is layered, with each set masked by a distinct circular hole centered in the viewport. The code uses the raw SVG DOM API via `document.createElementNS` to build masks, rectangles, and the masking circles, setting attributes like `mask` and `fill` directly. No JavaScript libraries are used; the result is a visible intersection of the two mask shapes across the rectangle layers.