JSFiddle - React, Tailwind, and code Playground

HTML

<div class="test">text</div>

CSS

.test {color: red}

.ie11 .test {color: green}

JavaScript

var isIE11 = navigator.userAgent.match(/Trident\/7.0; rv 11.0/);
if(isIE11) {
    document.querySelector('body').className += ' ie11';
}