First trial run at a basic plaid css pattern

html{
  background:
    linear-gradient(45deg, transparent 0%, transparent 5%, orange 5%, orange 20%, steelblue 20%, lightblue 30%, orange 30%, orange 45%, transparent 45%, transparent 55%, orange 55%, orange 70%, steelblue 70%, lightblue 80%, orange 80%, orange 95%, transparent 95%, transparent 100%),
        linear-gradient(-45deg,  transparent 0%, transparent 5%, yellow 5%, orange 20%, lightblue 20%, steelblue 30%, orange 30%, yellow 45%, white 45%, white 55%, yellow 55%, orange 70%, lightblue 70%, steelblue 80%, orange 80%, yellow 95%, transparent 95%, transparent 100%);
  background-size: 3em 3em;
  background-color: #FFF;
background-blend-mode: multiply, normal;
}