$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
}