Mã CSS:

linear-gradient(
  45deg,
  hsl(216deg 83% 12%) 0%,
  hsl(208deg 100% 17%) 11%,
  hsl(203deg 100% 23%) 22%,
  hsl(198deg 100% 27%) 33%,
  hsl(190deg 100% 29%) 44%,
  hsl(179deg 100% 29%) 56%,
  hsl(166deg 100% 34%) 67%,
  hsl(153deg 100% 39%) 78%,
  hsl(118deg 66% 57%) 89%,
  hsl(79deg 86% 50%) 100%
)