JSFiddle - React, Tailwind, and code Playground

HTML

<div class="posts-container">
    <div class="posts-column">
        <div class="post-item">
            1-1
        </div>
        <div class="post-item">
            1-2
        </div>
        <div class="post-item">
            1-3
        </div>
    </div>
    <div class="posts-column">
        <div class="post-item">
            2-1
        </div>
        <div class="post-item">
            2-2
        </div>
        <div class="post-item">
            2-3
        </div>
    </div>
    <div class="posts-column">
        <div class="post-item">
            3-1
        </div>
        <div class="post-item">
            3-2
        </div>
        <div class="post-item">
            3-3
        </div>
    </div>
</div>

CSS

div{
    box-sizing:border-box;
}
.posts-container{
    display:table;
    width:100%;
}
.posts-column{
    display:table-cell;
    width:33.333333%;
    padding:5px;
}
.post-item{
    width:100%;
    min-height:100px;
    background:#3cadb7;
    color:#fff;
    text-align:center;
    margin-bottom:10px;
}