message: Fix 1px space between file headers & diff toolbar
diff: @@ -659,7 +659,7 @@ a.tabnav-extra[href$='mastering-markdown/'] {
  /* Sticky file headers on pull request diff view */
  .pull-request-tab-content .diff-view .file-header {
  position: sticky;
  - top: 60px;
  + top: 59px;
  z-index: 10;
  }
  