This bar chart displays the population of the top 10 most populous countries, using 2018 estimates from the United Nations World Population Prospects. It demonstrates custom D3 axis styling, including formatted tick labels that convert billions to "B" and faint grid lines. The code uses `d3.scaleBand` for the categorical y-axis, `d3.scaleLinear` for the numeric x-axis, and `d3.axisLeft` and `d3.axisBottom` to render axes. A click handler on the body re-renders the visualization.