JSFiddle - React, Tailwind, and code Playground

HTML

<div class='d-table'>
    <div class='t-row'>
        <div class='t-cell one-third'>
            left
        </div>
        <div class='t-cell two-thirds'>
            <div class='t-row'>
                right 1
            </div>
            <div>
                right 2
            </div>
        </div>
    </div>
</div>

CSS

.d-table {
    display: table;
}
.t-row {
    display: table-row;
}
.t-cell {
    display: table-cell;
    border: 1px solid tomato;
}
.one-third {
    width: 100px;
}
.two-thirds {
    width: 200px;
}