This interactive stacked bar chart visualizes daily activity intensity for multiple users, sourced from Fitbit data in `dailyIntensities_merged.csv`. A dropdown menu switches between users, displaying four stacked segments—inactive, light, moderate, and intense activity—as proportions of a 1440-minute day. Built with ECharts 5.3.2, it uses the `bar` series with `stack: 'total'` for the bars, and adds translucent connecting polygons between adjacent bars via the `type: 'polygon'` element to highlight temporal transitions.