<div class="outer">
  <div class="inner">
    <span></span>
  </div>    
</div>
    
.outer {
  display: flex;
}
.inner {
  display: flex;
  flex-basis: 200px;
  max-width: 150px;
}
span {
  flex-basis:inherit;
}
document.body.appendChild(Object.assign(document.createElement('output'), { textContent:'inherited flex-basis =' + (getComputedStyle(document.querySelector('span')).flexBasis)
}));

External CSS

This Pen doesn't use any external CSS resources.

External JavaScript

This Pen doesn't use any external JavaScript resources.