JSFiddle - React, Tailwind, and code Playground

HTML

<div class="parent">
    <div class="child">
        <div>First</div>
    </div>

    <div class="container">
        <div>Second</div>
    </div>
</div>

CSS

body {
    background: #2b2e36;
    color: white;
    font-size: 20px;
}

.container {
    container-type: inline-size;
    background-color: green;
}

.parent {
    width: 100%;
    display: flex;
    justify-content: space-between;
    background: #ffff0061;
}

.child {
    background-color: #ff000091;
}