Pure CSS bunq rainbow

bunq.css

body {
  width: 100vw;
  height: 100vh;
}
body {
  background-image: linear-gradient(90deg,
      #238647,
      #238647 calc(100% / 12 * 1),
      #2F9B47 calc(100% / 12 * 1),
      #2F9B47 calc(100% / 12 * 2),
      #62B64F calc(100% / 12 * 2),
      #62B64F calc(100% / 12 * 3),
      #89CC53 calc(100% / 12 * 3),
      #89CC53 calc(100% / 12 * 4),
      #3DB8AD calc(100% / 12 * 4),
      #3DB8AD calc(100% / 12 * 5),
      #3394D7 calc(100% / 12 * 5),
      #3394D7 calc(100% / 12 * 6),
      #2872BC calc(100% / 12 * 6),
      #2872BC calc(100% / 12 * 7),
      #1D5C84 calc(100% / 12 * 7),
      #1D5C84 calc(100% / 12 * 8),
      #993233 calc(100% / 12 * 8),
      #993233 calc(100% / 12 * 9),
      #E13030 calc(100% / 12 * 9),
      #E13030 calc(100% / 12 * 10),
      #F28825 calc(100% / 12 * 10),
      #F28825 calc(100% / 12 * 11),
      #F5C836 calc(100% / 12 * 11),
      #F5C836 calc(100% / 12 * 12));
}