This example generates a full-screen SVG canvas filled with 85 vertical rectangles, each with a distinct blue-green color gradient. The rectangles are rendered using D3 v7’s `selectAll().data().join()` pattern, with dimensions and positions computed from an array of objects. Transitions are applied via CSS, causing all circles to slowly change color over two seconds, while hovering turns them grey with a lightseagreen stroke. The code relies on D3’s selection and data-binding methods, alongside custom styling in `styles.css`.