JSFiddle - React, Tailwind, and code Playground

JavaScript

var ss = document.createElement( "style" ),
    head = document.head || document.getElementsByTagName( "head" )[0] || document.documentElement,
    css = '@font-face {font-family: "TEST"; src: url("test.eot") format("eot");}';

ss.type = "text/css";    

if ( ss.styleSheet ){ 
    ss.styleSheet.cssText = css;
} 
else {
    ss.appendChild( document.createTextNode( css ) );
}

head.insertBefore(ss, head.firstChild );