This example creates a grid of thin horizontal and vertical rectangles using SVG, with two circular masks that reveal and hide portions of the lines. The pattern is generated through two loops that position 100 rectangles each, alternating their orientation. SVG mask elements define the visible area: one mask exposes a central circle of horizontal lines, while the other inverts the circle to show vertical lines outside the center. The rendering uses native JavaScript DOM manipulation via `createElementNS` to build the SVG structure dynamically, with no external libraries.