This example shows a bar chart of COVID-19 case counts for the top 20 countries, using the d3.csv loader to fetch data and React hooks (useState, useEffect) to manage asynchronous loading. It renders an SVG with green rectangles scaled by d3.scaleLinear for the x-axis and d3.scaleBand for the y-axis. The code also manually generates axis ticks and labels using d3.ticks and inline SVG elements, avoiding higher-level axis components. The visualization updates its dimensions through computed innerHeight and innerWidth margins.