li {
  background-image: paint(boxbg);
  --boxColor: hsl(55 90% 60% / 1);
}

li:nth-of-type(3n) {
  --boxColor: hsl(155 90% 60% / 1);
  --widthSubtractor: 20;
}

li:nth-of-type(3n + 1) {
  --boxColor: hsl(255 90% 60% / 1);
  --widthSubtractor: 40;
}