span.dmixer-original-price {
  position: relative;
  text-decoration: none !important;
}

span.dmixer-original-price::before {
  content: "";
  position: absolute;
  inset-inline-start: 0;
  inset-block-start: 50%;
  width: 100%;
  border-block-end: 1px solid red;
  transform: rotate(-15deg);
  pointer-events: none;
}