This bar chart displays the top 10 countries by 2020 population, drawn as horizontal rectangles scaled by population. The visualization uses D3 v5 (via `d3.csv`, `d3.scaleBand`, `d3.scaleLinear`, and `d3.max`) to parse the UN Population 2019 CSV data and compute the scales. React manages the chart's state with `useState` and `useEffect`, rendering the SVG elements dynamically. The margin constant (50 pixels on each side) offsets the plot area from the window edges, and the chart fills the entire browser viewport.