The flex-basis CSS property sets the flex-basis longhand, which specifies the flex basis: the initial main size of the flex item, before free space is distributed according to the flex factors.
Specifies the length using a number followed by a unit of measurement.
<percentage>
Specifies the percentage using a number followed by a percent sign (%).
min-content
Represents the largest min-content contribution of the items occupying the track.
max-content
Represents the largest max-content contribution of the items occupying the track.
fit-content()
Represents the formula max(minimum, min(limit, max-content)), where minimum represents an auto minimum (which is often, but not always, equal to a min-content minimum), and limit is the track sizing function passed as an argument to fit-content(). This is essentially calculated as the smaller of minmax(auto, max-content) and minmax(auto, limit).