JSFiddle - React, Tailwind, and code Playground

HTML

<ul>
    <li>
        aaaa
    </li><li>
        aaaa
    </li><li>
        aaaa aaa aaa aaa aaaa aaa aaa aaa aaaa aaa aaa aaa aaaa aaa aaa aaa aaaa aaa aaa aaa aaaa aaa aaa aaa aaaa aaa aaa aaa aaaa aaa aaa aaa aaaa aaa aaa aaa 
    </li><li>
        aaaa
    </li><li>
        aaaa
    </li>

CSS

ul {
    width:500px;
}

li {
    width:98px;
    display:inline-block;
    vertical-align:top;
    background-color:#dddddd;
    border: solid black 1px;
}

JavaScript

Elements.implement({
    setEqualHeight: function() {
        this.setStyle("height",  Math.max.apply(Math, this.map(function(el) { return el.getSize().y })));
    } 
});

document.getElements("ul li").setEqualHeight();