Customizing Axes
This bar chart displays the population of the top 10 most populous countries using 2018 United Nations estimates, with circles sized by population and custom axis styling. It demonstrates D3 v5 axis customization, including tick formatting that converts values like 'G' to 'B' for billions, rotated tick labels, and gridlines extending across the plot. The code uses `d3.csv`, `scaleLinear`, `scalePoint`, `axisBottom`, `axisLeft`, and `format` to render an SVG, with margins and labels styled via CSS.