A standalone SVG legend demonstrates how to encode categorical and quantitative data through color and size. The color legend maps fruit names (apple, lemon, lime, orange) to distinct hues using `d3.scaleOrdinal`, while the size legend uses `d3.scaleSqrt` to map a numeric domain from 0 to 10 to circle radii. Both legends are rendered as reusable components via the `colorLegend` and `sizeLegend` functions, positioned with appended SVG groups and `d3.select`. The example relies on D3 v5 and custom tick formatting.