JSFiddle - React, Tailwind, and code Playground

by Liu David

HTML

simply take away the overflow:auto property on the #ou div to see the difference.
overflow:auto will stretch the background div to the same height as its inner children.
<div id="ou">
    <div class="float">hi</div>
    <div class="float">hello</div>
</div>

CSS

.float { float: left;
    height: 200px;
    width: 150px;
    background: gray;
    margin: 0 5px;
}
#ou { background: yellow;
    overflow:auto;
}