JSFiddle - React, Tailwind, and code Playground

by iBird

HTML

<div id="bla">dfdf</div>

CSS

#bla {border: 1px solid #000;}

JavaScript

var FirstVar = 100;
var SecondVar = 50;
var calc = "calc("+FirstVar+"% - "+SecondVar+"px)"
document.getElementById("bla").style.width = calc;