JSFiddle - React, Tailwind, and code Playground

HTML

<div id="box">

<div id="header"><p>Header</p>
</div>

<div id="content">Content</div>

</div>

CSS

#box{
   background-color: lightgreen;
 }
 
#header{
 background-color: grey;
 float:right;
 width:150px;
 text-align: center;
 padding: 0px;
 margin: 0px;
}

#content {
 background-color: lightblue;
 clear:both;
}