This example displays a simple bar chart of letter counts from a CSV file, with clickable bars that highlight the selected letter and fade the others. Built with React and D3 v7, the React component manages state and dimensions via a `ResizeObserver`, while the D3 code uses `scaleBand` and `scaleLinear` to position bars, `axisBottom` and `axisLeft` for axes with gridlines, and `.join()` for data-driven SVG updates. The chart includes a title and axis labels rendered as SVG text.