JSFiddle - React, Tailwind, and code Playground

by vjeux

HTML

<div class="container">
    <div class="b">b</div>
    <div class="absolute">
        <div class="a">a</div>
    </div>
</div>

CSS

div {
    display: flex;
    flex-direction: column;
    opacity: 0.9;
    margin: 10px;
}
.container {
    background: black;
    height: 200px;
    position: relative;
}
.absolute {
    position: absolute;
    left: 0;
    right: 0;
    bottom: 0;
    top: 0;
    margin: 0;
    padding: 0;
}
.a {
    background: red;
}
.b {
    background: blue;
    flex: auto;
}