flex-direction: column; flex-wrap: wrap; with a fixed height. Once there’s no more vertical space, items wrap into a new column as they should. In Chrome, once items start wrapping into additional columns, the parent container’s width automatically grows to fit those new columns. In Firefox, the items do wrap into new columns, but the parent container’s width stays stuck at the size of the longest item (as if it hadn't wrapped), instead of expanding to hold all columns.inline-flex, width: auto;, width: fit-content, etc., but Firefox still just locks onto the width of the longest item.