A nearly blank canvas renders as a single rounded rectangle filling the browser viewport, sized dynamically to the window dimensions. The example demonstrates minimal D3.js usage with the `select` function to query an SVG element, then applies width and height attributes and appends a `rect` with a fixed corner radius. The visualization is purely geometric, with no data or interaction, serving as a template for React-based D3 projects. The styling enforces a fixed full-screen layout using CSS body rules.