Fundamentals3
The visualization shows a screen-filling grid of 100 horizontal bars, each 20 pixels apart, layered over the full viewport. Using D3’s `select` and data join, it renders SVG `rect` elements with dynamic height and width attributes. The code prepares circle-shaped masks, though they are not applied at runtime, leaving the bars plain. This example demonstrates fundamental D3 SVG rendering and data binding, with dimensions derived from `window.innerWidth` and `window.innerHeight`.