Build a responsive CSS Grid visually: set tracks, gap, flow and item alignment, optionally make one card span multiple cells, then copy the CSS. The preview uses real grid properties and runs entirely in the browser.
It gives each track an equal share of available space while allowing content to shrink below its intrinsic width. The 0 is a useful overflow guard for grids that contain long URLs, code snippets or images. Add your own media query if the number of columns should change at a particular screen width.