.code-block {
  position: relative;
}
.code-block button {
  position: absolute;
  top: 1rem;
  right: 1rem;
  z-index: 10;
  width: 1.25rem;
  height: 1.25rem;
  opacity: 0.0;
  color: white;
}
.code-block:hover button {
  opacity: 0.75;
}