JSFiddle - React, Tailwind, and code Playground

HTML

<div class="o">
    <div>a</div>
    <div>a</div>
    <div>a</div>
    <div>a</div>
    <div>a</div>
</div>
    
<div class="o flex">
    <div>a</div>
    <div>a</div>
    <div>a</div>
    <div>a</div>
    <div>a</div>
</div>

CSS

div.o
    {border:2px red solid;padding:2px;width:500px;flex-direction:row;display:flex;
    justify-content:flex-start}

div.o > div
    {border:2px red solid;margin:2px;}


div.o.flex > div
    {flex:1 1 auto;}