This example shows the monthly sales trend from 2021 to 2025 as a smooth line chart. The chart displays a single steelblue line with orange data points, with rotated month labels on the x-axis and a linear y-axis. Built with D3 v6, the code uses `d3.csv` to load `sales_trend.csv`, `d3.scaleTime` and `d3.scaleLinear` for axes, `d3.line` with `d3.curveMonotoneX` for the smoothed path, and `d3.axisBottom` and `d3.axisLeft` for tick marks. The SVG rendering includes a title and axis labels.