A static bar chart displays letter frequencies from a CSV file, with bars in teal that highlight and dim upon selection. Built with React and D3 v7, it uses `scaleBand` and `scaleLinear` for axes, `axisBottom` and `axisLeft` for ticks and gridlines, and a `ResizeObserver` to adapt the SVG to container dimensions. Clicking a bar toggles its selected state, which adjusts fill color and opacity.