This bar chart visualizes letter frequency data from a CSV file, displaying counts for letters A through G. Built with React and D3.js v7, the visualization features interactive bars that highlight and dim other bars when selected. The chart uses `d3.scaleBand` and `d3.scaleLinear` for positioning, with axes rendered via `d3.axisBottom` and `d3.axisLeft`. A `ResizeObserver` tracks container dimensions for responsive rendering, while D3's `.join` operations update the SVG elements efficiently.