JSFiddle - React, Tailwind, and code Playground

HTML

<div class="i-dont">
    <div class="i-float">
    </div>
    <div class="spacer"></div>
</div>

CSS

.i-dont {
    background-color: orange;
    border: 1px solid blue;
}
.i-float {
    height: 100px;
    width: 100px;
    background-color: red;
    float: left;
}

.spacer {
    clear:both;
}