This example demonstrates a minimal HTML page that combines CSS styling with D3 v6 and inline SVG to render two colored rectangles. The page sets a large body font size and centers the content, while the SVG drawing shows a red square overlaid with a smaller blue square. The code includes commented-out examples of D3 array methods like `d3.sum` and `d3.mean`, as well as data joins with `selectAll` and `append`, though these are not active. It serves as a bare-bones starter template for experimenting with SVG rendering and D3 syntax in a React-free environment.