A dark-themed dual-axis chart combines monthly visitor counts as cyan bars with conversion rates as a coral line, both plotted across twelve months from a CSV file. React manages state and lifecycle, while D3 v7 scales (`scaleBand`, `scaleLinear`) map the data; a `line` generator with `curveMonotoneX` smooths the conversion trend. The visualization includes value labels, gridlines, and separate left/right axes with formatted tick labels, all rendered as SVG elements.