body {
  position: relative;
}

body:after {
  position: absolute;
  width: auto;
  height: auto;
  z-index: 9999;
  content: '';
  display: block;
  pointer-events: none;
  top: 0;
  right: 0;
  bottom: 0;
  left: 0;
  background: url(./i/21);
  background-size: 4px 21px;
}

body:active:after {
  display: none;
}