html::after {
  -webkit-animation: wp-breathe 4s infinite ease-in-out;
          animation: wp-breathe 4s infinite ease-in-out;
  background-color: black;
  background-image: none;
  box-sizing: border-box;
  border: 0;
  content: '';
  height: 100%;
  left: 0;
  opacity: 0;
  outline: 0;
  pointer-events: none;
  position: fixed;
  top: 0;
  width: 100%;
  z-index: 10000000000000000;
}

@-webkit-keyframes wp-breathe {
  50% {
    opacity: .38;
  }
}

@keyframes wp-breathe {
  50% {
    opacity: .38;
  }
}