This example renders a horizontal bar chart of the top 10 most populous countries using React and D3.js v5, drawing SVG rectangles with `Marks.js` and labeling them with custom `AxisBottom` and `AxisLeft` components. The chart displays population values from the UN World Population Prospects 2019 dataset, loaded via `d3.csv` in `useData.js`. The x-axis uses a linear scale (`d3.scaleLinear`) and the y-axis a band scale (`d3.scaleBand`), but the visualization omits an explicit x-axis title or population gridlines, appearing sparse due to minimal margins and no tick labels on the x-axis. It relies on ReactDOM to mount the `App` component into the HTML page.