JSFiddle - React, Tailwind, and code Playground

HTML

<p>Hello, World!</p>
<div id="a"><span id="a1"></span></div>
<div id="b"><span id="b1"></span></div>

CSS

div { border:1px solid #000; height:30px; margin:1em; width:50% }
span {
    position:absolute;
    background:green;
    width:50%; height:20px;
    top:5px; left:5px
}
#a { background:red }
#b { backgrond:blue; position:relative }