This example demonstrates a minimal d3.js setup using a Model-View-Controller pattern, rendering a fixed lime-green rectangle and a centered "Hello World!" text message from `data.json` onto an SVG canvas. The code imports `select` from d3, fetches the JSON data via `d3.json`, and uses a separate `render.js` module to append the SVG shapes. The visualization is responsive, sizing the canvas to the browser window’s client dimensions.