textarea fully filling flex div

by Andy Bulka

HTML

<div class="gjs-row" id="ihpm">
  <div class="gjs-cell">
  
  <textarea name="out" title="this is the title of the textarea" width="auto" id="iyll">this is the initial content of the textarea - hello</textarea>
    
  </div>
  <div class="gjs-cell">

<div id="ib8h">Insert your text hereInsert your text hereInsert your text hereInsert your text hereInsert your text hereInsert your text hereInsert your text hereInsert your text hereInsert your text hereInsert your text hereInsert your text hereInsert your text here
    </div>

  </div>
</div>

CSS

* {
  box-sizing: border-box;
}
body {
  margin: 0;
}
.gjs-row{
  display:flex;
  justify-content:flex-start;
  align-items:stretch;
  flex-wrap:nowrap;
  padding-top:10px;
  padding-right:10px;
  padding-bottom:10px;
  padding-left:10px;
}
.gjs-cell{
  min-height:75px;
  flex-grow:1;
  flex-basis:100%;
}
@media (max-width: 768px){
  .gjs-row{
    flex-wrap:wrap;
  }
}

textarea {
  box-sizing: border-box; /* fit parent width */
  height: 100%;
  width: 100%;
}