This example demonstrates how SVG elements are constructed and layered directly in the browser using the Document Object Model (DOM) and the `createElementNS` API. It shows a series of vertical black lines evenly spaced across the viewport, followed by a single blue rectangle that fills the entire screen, obscuring the lines beneath it. The rendering approach relies on manual SVG creation via `document.createElementNS`, setting attributes for line coordinates and rectangle dimensions, and appending nodes to the document body. No external libraries are used; the code runs on raw JavaScript and SVG.