flex-basis
Flex base size
Flex basis specifies the main base size of flex items, If a flex
container’s flex-direction is column, this acts like the height
property, but if the direction is row, this acts like the width
property.
| Field | Value | 
|---|---|
| Cascades | No | 
| Initial value | auto | 
| Applies To | flex items | 
Values
Accepts any expression or value that resolves to a <length> value.
Examples
span {
  flex-basis: 25%;
}
span {
  flex-basis: 15px;
}