JSFiddle - React, Tailwind, and code Playground

HTML

<div id="outline">TEST</div>
<div id="another-div">Another div</div>

CSS

#outline {
    border: solid 1px #000;
    outline: solid 1px red;
    background-color: #fff;
    width: 200px;
    height: 200px;
}

#another-div {
    position: absolute;
    top: 100px;
    left: 100px;
    border: solid 1px #000;
    outline: solid 1px blue;
    background-color: #eee;
    width: 200px;
    height: 200px;
    z-index: 5000; /* even this is not helping */
}