Heat Map
A 5x5 heat map visualizes numeric values from a CSV file as colored squares, using a quantile scale with a sequential orange colormap to encode values from 1 to 20. The SVG rendering employs d3.csv for data loading, d3.scaleQuantile for color mapping, and d3.axisRight and d3.axisBottom to display axes. A tooltip appears on mouseover, showing the exact value of each cell.