Untitled
A simple HTML page containing a 100-pixel black square is animated inside a React application. The example demonstrates the `d3.transition()` API, which is used to smoothly change the background color of the `div` element from black to red over a duration of 3000 milliseconds. The page imports D3 v4 and uses `d3.select()` to target the container. The rendered output is a basic color transition, with no data input or complex rendering.