.copy-code-btn {
  position: absolute;
  top: 0.5rem;
  right: 0.5rem;
  padding: 0.2rem 0.6rem;
  font-size: 0.75rem;
  font-family: sans-serif;
  background: #fff;
  color: #333;
  border: 1px solid #ccc;
  border-radius: 4px;
  cursor: pointer;
  opacity: 0;
  transition: opacity 0.2s;
}

pre:hover .copy-code-btn {
  opacity: 1;
}

.copy-code-btn:hover {
  background: #f0f0f0;
}