JSFiddle - React, Tailwind, and code Playground

HTML

<div id="one">
    <div id="oneone"></div>
    <div id="two"></div>    
</div>

CSS

#one {
    position:absolute;
    background-color:#999;
    width:200px;
    height:200px;
    z-index:1;
}
#oneone {
    position:absolute;
    background-color:#fff;
    width:50px;
    height:50px;
    left:100px;
    top:90px;
    z-index:5;
}
#two {
    position:absolute;
    background-color:#000;
    width:200px;
    height:200px;
    left:200px;
    top:290px;
    z-index:20;
    display:none;
}
#oneone:hover + #two {
    display:block;
}