CODE EXAMPLE FOR CSS

repeating-linear-gradient

body {
  background-image: repeating-linear-gradient(-45deg,
      transparent,
      transparent 20px,
      black 20px,
      black 40px);
  /* with multiple color stop lengths */
  background-image: repeating-linear-gradient(-45deg, 
      transparent 0 20px, 
      black 20px 40px);
}