JSFiddle - React, Tailwind, and code Playground

HTML

<div>
    <div class="col">
        <div class="pane"></div>
    </div>
    <div class="col">
        <div class="pane"></div>
        <div class="pane"></div>
    </div>
</div>

CSS

.col {
    display: inline-block;
    float: left;
    overflow: hidden;
    border: 1px solid white;
}

.col:first-child {
    max-width: 12vw;
}

.pane {
    background-color : red;
    border: 2px dotted yellow;
    min-width: 20vw;
    min-height: 20vh;
}