A grid of black-outlined squares creates an optical illusion where overlapping stroke widths produce dense circular patterns at each junction. The visualization is built with React and renders an SVG, mapping a 10x10 array of rectangles with thick 25-pixel strokes. The code computes positions using a fixed square size of 100 pixels and draws both inner rectangles and a surrounding boundary. All shapes have no fill, relying solely on the stroke styling to generate the visual effect.