Heatmap

- https://nivo.rocks/heatmap/
- https://github.com/airbnb/visx/tree/master/packages/visx-heatmap
- https://commit-analyzer.vercel.app/contributions
  - https://github.com/techniq/github-commit-analyzer/blob/master/src/routes/contributions.svelte#L178-L199
- https://observablehq.com/@d3/the-impact-of-vaccines