JSFiddle - React, Tailwind, and code Playground

HTML

<div class="parent" id="a">
    <div class="child">a</div>
</div>
<div class="parent" id="b">
    <div class="child">b</div>
</div>

CSS

.parent{
    position: relative;
    color:white;
}
.parent#a {
    height: 2em;
    z-index: 1;
}
.parent#a .child{
    position: absolute;
    height: 6em;
    width: 2em;
    z-index:1;
    background:blue;
}
.parent#b {
    height: 2em;
    background:red;
}