message: Fix z-index for showing "open pull request" shortcut
diff: @@ -793,7 +793,7 @@ a.tabnav-extra[href$='mastering-markdown/'] {
  position: absolute;
  top: -117px;
  right: 0;
  - z-index: 10;
  + z-index: 32; /* Set z-index higher than ul.pagehead-actions */
  background: var(--github-gray-background);
  white-space: nowrap;
  animation: rgh-slide-in-right 0.3s ease-out;
  