This example demonstrates two custom D3.js legend components rendered as SVG. A color legend uses `scaleOrdinal` with categorical domains to map fruit names to distinct colors, while a size legend uses `scaleSqrt` to map a numeric range to circle radii. Both legends are built by dynamically appending `g` groups with circle and text elements, using D3's enter/merge/exit pattern for updates. The code relies on D3 v5 selection methods and scale APIs to generate the visual encodings.