JSFiddle - React, Tailwind, and code Playground

HTML

<div id="div1">hover over me</div>
<div id="div2"></div>

CSS

#div2 {
    width: 200px;
    height: 200px;
    background: red;
    display: none;
    transition: 1.8s;
}
#div1:hover ~ #div2 {
    display: block;    
}