JSFiddle - React, Tailwind, and code Playground

by bgrins

HTML

<div id="log"></div>

CSS

:root {
    --theme-body-background: rgba(100,100,3, .3);
}

JavaScript

var dummy = document.createElement("div");
dummy.textContent = "dummy element";
dummy.style.backgroundColor = "var(--theme-body-background)"; 
document.body.appendChild(dummy);

document.querySelector("#log").textContent = window.getComputedStyle(dummy).getPropertyValue("background-color");