pre[class*=language-] {
  position: relative;
  border-radius: 10px;
}
pre[class*=language-] .copy {
  content: "copy";
  padding: 2px 10px 0;
  position: absolute;
  top: 10px;
  right: 10px;
  opacity: 0;
  border-radius: 5px;
  color: white;
  background: #272822;
  cursor: pointer;
  transition: all 200ms ease;
}
pre[class*=language-]:hover .copy {
  opacity: 1;
}
pre[class*=language-]:hover .copy:hover {
  color: gray;
}