Three overlapping translucent squares in red, green, and blue demonstrate RGB color theory through additive color mixing. Rendered as React components with SVG circles and rectangles, the visualization uses `MyRect` and `MyCircle` exports from `exports.js` to position three 250-pixel squares at offsets from the center of a 960×500 viewport with 0.9 opacity. D3 v5 sets the SVG dimensions while React 16.12 manages component rendering into the `#root` element.