Customizing Axes
This example presents a horizontal bar chart of the top 10 most populous countries using 2018 United Nations population estimates. The chart demonstrates D3 axis customization, using `d3.axisBottom` with `.tickFormat` to abbreviate population numbers (converting "G" to "B"), custom tick sizes that extend through the chart, and hidden domain lines. It also uses `d3.scaleBand` and `d3.scaleLinear` to map countries and populations, with SVG rendered bars and styled text labels.