This example demonstrates a workflow for loading external data into a D3.js visualization. It shows how a container element initializes with an undefined data state, triggering a fetch request for a `data.csv` file, and then adapts to the data as it becomes available. The code uses D3 v7 and the `fetch` API to asynchronously load the data, with the visualization re-rendering on window resize events. The implementation relies on a modular structure with separate files for the HTML, main script, and visualization logic.