JSFiddle - React, Tailwind, and code Playground

HTML

<p>Check this example in chrome:</p>
    <ul>
        <li>Why does .outer have the width as if it was flex-flow: row nowrap; ?</li>
        <li>Why does .outer have a height as if it has a single row?</li>
    </ul>
    <div class="root">
        <div class="outer">
            <div class="inner">A</div>
            <div class="inner">B</div>
            <div class="inner">C</div>
            <div class="inner">D</div>
            <div class="inner">E</div>
            <div class="inner">F</div>
            <div class="inner">G</div>
            <div class="inner">H</div>
            <div class="inner">I</div>
            <div class="inner">J</div>
        </div>
    </div>

CSS

body{
            margin: 0;
            padding: 0;
        }
        
        .root{
            display: flex;
        }

        .outer{
            background-color: red;
            display: flex;
            flex-flow: column wrap;
            align-content: flex-start;
            flex: 1 0 auto;
            max-height: 400px;
        }

        .inner{
            background-color: violet;
            border: 1px solid black;
            height: 100px;
            width: 100px;
            flex: 1 0 auto;
            color: white;
            text-align: center;
            font-size: 50px;
        }