JSFiddle - React, Tailwind, and code Playground

HTML

<div class="flexman">
    <div></div>
    <div></div>
    <div></div>
    <div></div>
</div>

CSS

.flexman {
    padding: .2vw;
    display: -ms-flexbox;
    -ms-flex-wrap: wrap;
    -ms-flex-direction: column;
    -webkit-flex-flow: row wrap;
    flex-flow: row wrap;
    display: -webkit-box;
    display: flex;
}
.flexman div {
    background: red;
    -webkit-box-flex: 1 auto;
    -ms-flex: 1 auto;
    flex: 1 auto;
    width: 400px;
    margin: .2vw; 
}