Test d3.js
A full-window SVG rectangle with rounded corners serves as the sole visual element, filling the available viewport dimensions. The example demonstrates basic D3.js v5 setup by importing the `select` function to target the SVG element, then using chained attributes to set its width and height based on `document.body.clientWidth` and `document.body.clientHeight`. A single `rect` is appended with matching dimensions and a 40-pixel corner radius, styled through minimal CSS that disables page scrolling. This provides a minimal, interactive-free baseline for testing D3 rendering in a blank canvas.