JSFiddle - React, Tailwind, and code Playground

HTML

<div id="square1">1</div>
<div id="square2">2</div>

CSS

#square1, #square2 {
    width: 100px;
    height: 100px;
    text-align: center;
    vertical-align: middle;
    line-height: 100px;
    position:absolute;
    
}
#square1 {
    background-color: #f00;
    z-index:1;
}
#square2 {
    background-color: #A44;
    z-index:1000;
}