Choose the number of columns and rows and the gap size, preview the grid live, and copy the grid-template CSS to drop into your container.
fr means a fraction of the available space, so 1fr 1fr splits a row into two equal flexible columns.
Grid is two-dimensional, laying out rows and columns together, while Flexbox handles one dimension at a time.
Use repeat(auto-fit, minmax(...)) so columns automatically wrap and resize to fit the container width.