CSS navbar and color tweaks (#13609)

* CSS and color tweaks

- Unify navbar-style menus
- Fix admin bar overlapping menu bar
- Fixes file edit comment box
- Fix double border on review box
- Fix review timeline icons

* Many fixes to new-menu and navbar layout enhancements

* misc settings fixes

* navbar tweak

* fix pr tabs

* branch tag and arc color tweaks

web_src/less/_review.less

@@ -180,3 +180,7 @@ a.blob-excerpt:hover {
     max-width: 900px;
   }
 }
+
+.review-box > .segment {
+  border: none !important;
+}