html {
  background: /* 1 */
    var(--pattern, 
      radial-gradient(closest-side, #777, #fff) 
        0/ 1em 1em space), 
    var(--map, 
      linear-gradient(90deg, #888, #fff));
  background-blend-mode: multiply /* 2 */;
  filter: contrast(21) /* 3 */
}