This example demonstrates a minimal D3.js visualization that renders an SVG element and displays the text "Hello world" in the DOM. It loads D3 v5 from UNPKG and uses the `d3.selectAll` API to target the SVG, though no visual marks are drawn. The code imports a local ES6 module (`myMessage.js`) to show modular JavaScript in a VizHub project. Styling is handled externally via CSS for the message div.