$c: #e8122e #f5ec07 #0662f5;
$b: #161125;
$d: 6em;

/* compiled code is under 200 bytes minified ;) */
html {
	background: 
		linear-gradient(135deg, 
				$b 16.66%, 
				transparent 0 83.33%, 
				$b 0), 
		conic-gradient(from 45deg 
				at 66.66% 33.33%, 
				nth($c, 1) 135deg, 
				nth($c, 2) 0% 225deg, 
				nth($c, 3) 0%);
	background-size: $d $d
}
View Compiled

External CSS

  1. https://codepen.io/thebabydino/pen/evPbxv.scss

External JavaScript

  1. https://codepen.io/thebabydino/pen/evPbxv.js