html {
  background:#475769;
  background-image:
    repeating-linear-gradient(to right, 
      transparent 0,
      transparent 9px, 
      #456 9px, 
      #345 10px
    )
    ,
    repeating-linear-gradient(to bottom, 
      transparent 0,
      transparent 9px, 
      #234 9px, 
      #456 10px
    ),
    linear-gradient(
      to bottom left ,
      rgba(0,0,0,0.05), 
      rgba(255,255,255,0.05))
    ;
  background-size: .65em .65em;
}
html:hover {
  animation:bgsize 1s infinite ;
}
@keyframes bgsize {
  50% {
    background-size:1.3em 1.3em;
  }
}