This example demonstrates basic SVG shape primitives within a standalone HTML document, rendered directly in the browser’s SVG namespace. It shows a row of three colored circles (black, red, and yellow), followed by a large red rectangle with a navy stroke and a diagonal navy line. The code uses plain SVG elements—`circle`, `rect`, and `line`—with explicit attributes for positioning, fill colors, and stroke properties. No JavaScript libraries are involved; the rendering relies solely on the browser’s native SVG support, with a brown background set on the body element.