JSFiddle - React, Tailwind, and code Playground

HTML

<title>Mandelbrot Set</title>
<div id="out"></div>

CSS

#out {
    font-size:1px;
    width:300px;
    word-wrap:break-word;
}

JavaScript

// This is a 140byt.es entry, hosted at https://gist.github.com/1257323 
  // initiated by @sylvinus, golfed down to death by @fgnass !
  
    var mandelbrot =
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
function(z,s,r,i,k,n,w){for(w=z*z,n=w;n--;s[w-n]='█'.fontcolor('#'+k*9))for(r=i=k=0;r*r+i*i+k++<z;i=t)t=2*r*i+1-2*n/w,r=r*r-i*i+1-3*n/z%3}


var a = [];
mandelbrot(300,a); //First parameter is the render width. Change it here and in the CSS
document.getElementById('out').innerHTML = a.join('');