JSFiddle - React, Tailwind, and code Playground

HTML

<div class="table-layout">
    <div class="table-cell fixed-width-200">
        <p>fixed width div</p>
    </div>
    <div class="table-cell">
        <p>fluid width div</p>    
    </div>
</div>

CSS

.table-layout {
    display:table;
    width:100%;
}
.table-layout .table-cell {
    display:table-cell;
    border:solid 1px #ccc;
}

.fixed-width-200 {
    width:200px;
}