JSFiddle - React, Tailwind, and code Playground

HTML

<div class="row">
    <div class="cell1 cell">
        <div class="inner">
            <h2>Cell 1</h2>
            <p>Regardless of content, can I make Cell 1 and Cell 2 the same height so the borders are level?</p>
            <p>Even with more content.</p>
        </div>
    </div>
    <div class="cell2 cell">
        <div class="inner">
            <h2>Cell 2</h2>
        </div>
    </div>
</div>

CSS

.cell {
    width: 50%;
    background: #eee;
    float: left;
    margin-bottom: -1000px;
    padding-bottom: 1000px;
}

.cell:nth-child(odd) { background: #ddd; }

.row { overflow: hidden; }

.row:after {
    content: "";
    clear: both;
    display: table;
}