This example loads and displays monthly average atmospheric CO₂ measurements from the NOAA Global Monitoring Laboratory at Mauna Loa. It strips comment lines from the CSV, parses the data, and shows a proof-of-life summary with the first six rows in a styled HTML container, including a row count. The visualization uses `d3.csvParse` to handle the data and `d3.select` to target the container element, with the D3 v7 library loaded via a CDN.