This visualization combines bars and lines to compare daily fitness metrics—calories burned, steps walked, and active minutes—across 150 days. It shows all three trends on a single SVG chart, with steps scaled down to fit the axis. The code uses D3 v7 APIs such as `scaleBand`, `scaleLinear`, `axisLeft`, and `d3.line` to render the chart, while React handles the page setup. Data comes from a CSV file loaded via `d3.csv`, and the rendering uses SVG elements like `rect` and `path`.