JSFiddle - React, Tailwind, and code Playground
HTML
<div id="container">
<div id="cube">
</div>
</div>CSS
div{
outline:1px solid red;
}
#container{
width:200px;
height:30px;
}
#cube{
width:30px;
height:100%;
background-color:red;
}
#container:hover #cube {
width:30px;
height:100%;
background-color:blue;
}