A heatmap visualizes correlations among six factors—GDP per capita, social support, healthy life expectancy, freedom, generosity, and perceptions of corruption—for the top ten happiest countries, with data from a CSV file. Panels flanking the heatmap list the top five countries, each shown as a circle containing its flag via SVG images. The code uses d3.scaleSequential with interpolateRdBu, d3.flatMap for matrix computation, Pearson correlation from helper functions, and animated opacity transitions with random delays.