The Flex Basis property specifies the initial size of a flex item before extra space in the container is distributed. This is used in place of the width property in the flex layout.
Flex basis can accept values in Pixels (100px), Percentages (100%), ems (100em), rems (100rem) and keywords like auto. The default value is set to auto which sets the initial width based on the content of the item.
See the Pen Flex Basis by rehmaanali (@geekstrick) on CodePen.