message: fix(aio): ignore `.header-link` when selecting the heading text
  Implemented
  [suggestion](https://github.com/angular/angular/issues/21515#issuecomment-357453634).
  Fixes
  PR Close
diff: margin-left: -42px;
  padding: 0 8px;
  text-decoration: none;
  + user-select: none;
  vertical-align: middle;
  visibility: hidden;
  width: 40px;
  