JSFiddle - React, Tailwind, and code Playground

HTML

<ul>
    <li>a</li>
    <li>b</li>
    <li>c</li>
    <li>d</li>
    <li>e</li>
    <li>f</li>
    <li>g</li>
    <li>h</li>
    <li>i</li>
    <li>j</li>
    <li>k</li>
</ul>

CSS

html, body { height: 100%; }

ul {
    display: flex;
    flex-wrap: wrap;
    height: 100%;
    list-style: none;
    padding: 0;
    align-content: flex-start;
}

li {
    flex: 0 1 200px;
    background: pink;
    height: 100px;
    line-height: 100px;
    text-align: center;
    box-sizing: border-box;
    margin: 15px;
}