JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
    <div class="left"></div>
    <div class="right"></div>
</div>

CSS

* {
   margin: 0;
   padding: 0;
   -moz-box-sizing: border-box;
   -webkit-box-sizing: border-box;
   box-sizing: border-box;
}

.container:after {
    clear: both;
}

.container > div {
    min-height: 200px;
    float: left;
    width: 50%;
}

.left {
    background: #f00;
}

.right {
    background: #f0f;
}

@media all and (max-width: 500px) {
    .container > div {
        float: none;
        width: 100%;
    }
}