A stacked dashboard of two SVG charts visualizes 150 days of simulated environmental data from a CSV file. The top multi-series line chart maps temperature, humidity, and air-quality index over time using `d3.line` and `d3.scaleOrdinal` for series colors, with axes and a legend. Below, a combined chart pairs bars for the air-quality index (`d3.scaleBand`, rects) with a temperature line over the same x-axis. Both charts share a common day axis, built with D3 v7 scales, axes, and shape primitives.