feat: add mixed string for border side toggling support

Author: devvaannsh

src/nls/root/strings.js

@@ -210,7 +210,8 @@ define({
     "LIVE_DEV_STYLER_RESET": "Reset changes",
     "LIVE_DEV_STYLER_NOTHING_TO_RESET": "No changes to reset",
     "LIVE_DEV_STYLER_CLOSE_SAVED": "Done",
-    "LIVE_DEV_STYLER_SELECT_ELEMENT": "Select an ancestor element",
+    "LIVE_DEV_STYLER_MIXED": "Mixed",
+    "LIVE_DEV_STYLER_SIDES_MIXED": "Sides differ — edit each side separately",
     "LIVE_DEV_STYLER_SEARCH_FONTS": "Search fonts…",
     "LIVE_DEV_STYLER_FONTS_GOOGLE": "Google",
     "LIVE_DEV_STYLER_FONTS_SYSTEM": "System",