This generative visualization creates an "X" composition using two overlapping white rectangles, with horizontal lines visible only inside the X and vertical lines appearing only outside it. Built with raw JavaScript and the SVG API, the sketch uses `<mask>` elements to control line visibility: a mask with black X shapes hides vertical strokes inside the form, while an inverse mask reveals horizontal strokes only within the X. Black horizontal and vertical bars are drawn in loops at 20-pixel spacings, each masked to achieve the alternating pattern across the full viewport. The piece dynamically sizes to the browser window and uses no external libraries.