This example demonstrates two custom legend components for D3 visualizations: a color legend matching ordinal categories to specific colors, and a size legend using a square-root scale to map numeric values to circle radii. The color legend renders labeled circles for fruits like apple and lemon, while the size legend displays five tick marks with proportional circle sizes. Both legends are built using D3 v7’s selection-merging API, appending SVG `<g>` groups to position circles and text labels with translated transforms.