Episode 4 _ 2 - no duplicated logic
A grid of ninety-nine thin horizontal and vertical rectangles, clipped by two mask shapes, creates an overlapping lattice pattern. The visualization uses D3 v6 selections and data joins to append SVG rectangles and paths. A reusable `renderMask` function builds two masks, each containing a centered symbol from `d3.symbol` and `d3.range`. One mask inverts its fill to reveal the vertical bars, while the other hides them, producing alternating visible segments across the full browser viewport. The SVG renders at high resolution with rectangle thickness and spacing determined by array indices.