JSFiddle - React, Tailwind, and code Playground

HTML

<div id="header">WIDTH</div>

CSS

#header {
    margin: 8px;
    font-size: 40px;
    display:inline;
    padding: 8px;
    position:absolute;
    white-space:nowrap;
    overflow:hidden;
    border:thin solid #bbb;
}

JavaScript

var text_div = document.getElementById("header");
var initWinW = window.innerWidth;
var initFontSize = 40;

var size = function () {
    var winW = window.innerWidth;
    var textFactor = winW / initWinW
    text_div.style.fontSize = initFontSize * textFactor + "px";
}

window.onresize = function () {
    size();
}