HTML Starter
This example shows a minimal setup for creating a D3 visualization in a web page. It renders a single circle with a radius of 200 pixels inside an SVG container. The code imports the `select` function from the D3 library, selects the existing SVG element, appends a circle to it, and sets its radius attribute. The page loads D3 v5 from a CDN and includes separate HTML, CSS, and JavaScript files.