A pie chart visualizes the distribution of CSS named colors grouped by their first letter, showing the top 12 alphabetical categories with counts and percentages. The d3.v7 library loads CSV data from a GitHub gist, aggregates entries by initial character, and renders an SVG pie chart with ordinal color encoding, hover-to-scale effects, and interactive tooltips. Mouseover events trigger animated scaling and display details on category count and proportion, while a legend and title provide context.