Two interactive color legends let users select a MIDI file and then one of its tracks from a local dataset. The legends use d3.scaleOrdinal and d3.schemeSpectral for the file palette, while tracks use a scale with a numeric range. Clicking a legend item highlights it at full opacity, dims unselected items to 0.2 opacity, and triggers callbacks to re-render both legends. The code imports colorLegend from a separate module and renders SVG text and circles into groups.