flex-basis: auto
flex-basis: auto
flex-basis: auto

all auto⤴

flex-basis: auto;
width: 100px;
flex-basis: auto;
width: 150px;
flex-basis: auto;
width: 200px;

widths declared⤴

flex-basis: auto
flex-basis: auto
flex-basis: 100%

single basis declared @ 100%⤴

flex-basis: 70%
flex-basis: auto
flex-basis: 80%

more than 100% total flex-basis⤴