This fork of a Chart.js line chart renders monthly temperature variations across three years as a stacked area chart, with the chart type set to `line` and line filling enabled. The code defines a custom `gradientColor` function using Canvas’ `createLinearGradient` to generate per-dataset area backgrounds. It includes interactive features via the `chartjs-plugin-zoom`, enabling wheel and pinch zooming in both x and y dimensions, plus tooltips and a bottom legend. The chart is drawn on a canvas inside an HTML container, with sample data hardcoded for San Francisco.