This interactive bar chart displays letter frequency data from a CSV file, with clickable bars that highlight and dim based on user selection. Built as a React and D3.js integration, it uses `ResizeObserver` for responsive dimensions, `scaleBand` and `scaleLinear` for scales, and `axisBottom`/`axisLeft` for axes with gridlines. The bars feature smooth color and opacity transitions, with a static title and axis labels rendered via D3 selections.