Pick flex-direction, justify-content, alignment, wrap and gap (or grid columns and gaps) and see the layout update live, then copy the generated CSS.
Flexbox is best for one-dimensional layouts (a row or a column); Grid excels at two-dimensional layouts with rows and columns.
In flex, justify-content positions items along the main axis and align-items along the cross axis; grid uses justify-items/align-items per cell.
Yes — the output targets a .container class you can drop straight into your stylesheet.