A grid of thin horizontal and vertical bars covers the full screen, creating intersecting lines that are visible only through a central circular mask, leaving the corners dark. The bars are drawn as SVG rectangles using D3’s `selectAll().join()` pattern with `range()`-generated data. Two masks define the view: one white circle reveals the inner bars, while a second mask with an inverted circle hides the outer bars’ center. The example uses D3 v7 and SVG rendering with no external data source.