.master {
  max-width: 50%;
}

.master::before {
  content: "";
  display: inline-block;
  width: 50%;
  height: 100%;
  background: var(--master-decoration-url) center/contain no-repeat;
  position: fixed;
  top: 0;
  right: 0;
  transform: scaleX(-1);
  z-index: -1;
}

@media screen and (max-width: 768px) {

  .master {
    max-width: 100%;
    margin-top: 15%;
  }

  .master::before {
    position: absolute;
    width: 100%;
    height: auto;
    aspect-ratio: 2;
    top: 5%;
  }
}