This example reproduces a Sol LeWitt wall drawing using only HTML and JavaScript. It shows a grid of black horizontal and vertical lines intersecting within two circular areas at the center of the canvas. The rendering relies on the Document Object Model (DOM) to create SVG elements programmatically, including `<rect>` elements for the lines and `<mask>` elements to clip the lines into circular shapes. No external libraries are used; the design is generated with a pair of nested loops to fill the entire viewport with the alternating line patterns.