JSFiddle - React, Tailwind, and code Playground

HTML

<ul>   
        <li>Block</li>
        <li>Block</li>
        <li>Block</li>
        <li>Block</li>
        <li>Block</li>
        <li>Block</li>
        <li>Block</li>
        <li>Block</li>

</ul>

CSS

ul li { height: 100px; width: 100px; border: 1px #000 solid; float: left; }
li:nth-child(3n+1) { clear: left; }
li:first-child, li:nth-child(3n+1) { background: red; }