This example displays the text “Hello D3 version 7” centered in the browser using D3 v7. The page sets a large font size and uses `d3.select` to insert the message into the body element. It also includes utility code that creates a downloadable text file via the Blob API, though this feature is not actively triggered on load. The simple demonstration shows how to begin working with D3 version 7 in a minimal HTML setup.