JSFiddle - React, Tailwind, and code Playground

JavaScript

var d = document, tiles = ["\u2571","\u2572"], i = 0, s = 12, b, s, l;

d.open();
d.write("<html><body>");
b = d.body;
b.style.cssText = "font-size:" + s + "px;"
b.style.cssText += "word-wrap:break-word;padding:0;margin:0;line-height:100%";
l = Math.floor(b.clientHeight/s) * Math.floor(b.clientWidth/s);

while (i < l) { 
  d.write(tiles[Math.round(Math.random())]);
  i++;
}
 
d.write("</body></html>")
d.close();