This stacked bar chart displays the distribution of subgroups across categorical groups, with each bar segment colored by subgroup and stacked to show cumulative values. The visualization is built using D3 v4, loading CSV data from GitHub, and rendering SVG rectangles with a band scale for the x-axis and a linear scale for the y-axis. It uses `d3.stack()` to compute stacked values, `d3.scaleOrdinal` for colors, and includes an interactive tooltip element in the HTML structure.