This example demonstrates how a visualization can automatically respond to changes in the browser window size. A green X-shaped pair of lines is always drawn to fill the entire viewport, with the SVG’s width and height updated dynamically on every resize event. The code reads the `clientWidth` and `clientHeight` of a fixed-position container div, then uses those values to set the SVG attributes and redraw the lines via a custom `redraw` function. It uses D3 v5 for SVG selection, data binding, and element merging.