Updated Tips (markdown)

Tips.md

@@ -5,6 +5,17 @@
 - [Download Behavior FF v98 above](https://www.reddit.com/r/firefox/comments/tdohiy/firefox_98_download_manager_support_thread/)
 - [Linux VA-API](https://www.reddit.com/r/firefox/comments/r5wilh/the_road_to_vaapi_on_linux_by_default_looks/)
 
+## Sync UI
+
+Refer:
+- https://support.mozilla.org/en-US/kb/sync-custom-preferences
+- https://firefox-source-docs.mozilla.org/modules/libpref/index.html#sync
+
+**Apply**
+- `services.sync.prefs.dangerously_allow_arbitrary` to `true`
+- `services.sync.prefs.sync.browser.uiCustomization.state` to `true`
+- `services.sync.prefs.sync.browser.uidensity` to `true`
+
 ## Privacy
 
 Please refer to the following settings: