JSFiddle - React, Tailwind, and code Playground

HTML

<div id="outer-container">
<div id="inner-div" contenteditable=true></div>
</div>

CSS

#outer-container {
    padding: 2em 0;
    background-color: #CCC;
}
#inner-div{
  border: 1px solid #000;
}
#inner-div:not(:empty) + #outer-container{
    background-color: yellow;
}