This D3.js (v6) example visualizes the highest salaries by company location from a data science salaries CSV, comparing the COVID-19 period (2020–2022) with the post-COVID years (2023–2024) using two stacked bar charts. It employs `d3.csv` to load the data, `d3.rollup` to aggregate maximum salaries by location, and `d3.scaleLinear`, `d3.scaleBand`, and `d3.axisBottom`/`d3.axisLeft` to construct the charts. The SVG output renders bars as rectangles with hover effects, showing the top 20 locations for each period.